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# Testing Methodologies Standards for CMake This document outlines the coding standards for testing methodologies in CMake projects. It covers unit, integration, and end-to-end testing strategies specifically within the CMake context, emphasizing modern approaches and best practices. ## 1. General Testing Principles ### 1.1 Clarity and Organization * **Do This:** Structure tests clearly, with descriptive names for test files, test targets, and individual test cases. Aim for self-documenting tests that explain WHAT is being tested and WHY. * **Don't Do This:** Use cryptic or abbreviated names that obscure the purpose of the test. Avoid large, monolithic test files that test too many unrelated components. * **Why:** Clarity enhances maintainability. Well-organized tests are easier to understand, debug, and extend, preventing test rot and promoting confidence in the codebase. """cmake # Good: add_test(NAME MyLibrary_StringUtil_Trim_LeadingWhitespace COMMAND ${CMAKE_CTEST_COMMAND} -C $<CONFIG> -R "MyLibrary_StringUtil_Trim_LeadingWhitespace" ) # Bad: add_test(NAME test1 COMMAND ${CMAKE_CTEST_COMMAND} -C $<CONFIG> -R "test1") """ ### 1.2 Test-Driven Development (TDD) * **Do This:** Consider adopting TDD principles, writing tests *before* implementing the code that satisfies them. * **Don't Do This:** Write tests as an afterthought. Tests should drive the design and implementation of the feature. * **Why:** TDD encourages better design, reduces bugs, and leads to more testable code. It also provides immediate feedback on changes. ### 1.3 Independent Tests * **Do This:** Ensure each test is independent from other tests. Tests should not rely on the side effects of previous tests. * **Don't Do This:** Create test suites with dependencies between tests. This makes debugging and reasoning about failures extremely difficult and can lead to cascading issues. * **Why:** Independence prevents cascading failures and makes tests easier to reason about and debug. ### 1.4 Test Data Management * **Do This:** Use realistic and relevant test data, but avoid complex or excessive data that obscures the test's purpose. Consider generating test data programmatically for complex scenarios. * **Don't Do This:** Hardcode unrealistic or minimal test data that doesn't reflect real-world use cases. * **Why:** Realistic test data increases confidence that the code works in production-like environments. ## 2. Unit Testing ### 2.1 Framework Selection * **Do This:** Use a modern C++ testing framework like Google Test, Catch2, or doctest. Integrate the framework into your CMake project using "FetchContent" or "find_package". * **Don't Do This:** Roll your own testing framework. Rely on "printf"-style debugging or manual inspection. * **Why:** Established frameworks provide powerful features like assertions, test organization, mocking, and reporting. """cmake # Example using FetchContent and Google Test (gtest) include(FetchContent) FetchContent_Declare( googletest GIT_REPOSITORY https://github.com/google/googletest.git GIT_TAG v1.14.0 # Use a specific version ) FetchContent_MakeAvailable(googletest) add_executable(MyLibraryTests test/MyLibraryTests.cpp) target_link_libraries(MyLibraryTests MyLibrary gtest_main) include(GoogleTest) gtest_discover_tests(MyLibraryTests) """ ### 2.2 Test Structure * **Do This:** Organize unit tests into well-defined test cases targeting specific functions or classes. Use a common pattern for test case naming (e.g., "ClassName_MethodName_Scenario"). * **Don't Do This:** Mix multiple tests within a single large test function. Use overly broad test cases that try to test everything at once. * **Why:** Fine-grained tests pinpoint the source of failures more easily than blanket tests. """cpp // Example using Google Test #include "MyLibrary.h" #include "gtest/gtest.h" TEST(StringUtil_Trim_LeadingWhitespace, EmptyString) { std::string str = ""; MyLibrary::trim(str); ASSERT_EQ(str, ""); } TEST(StringUtil_Trim_LeadingWhitespace, StringWithLeadingSpaces) { std::string str = " Hello"; MyLibrary::trim(str); ASSERT_EQ(str, "Hello"); } """ ### 2.3 Mocking and Isolation * **Do This:** Use mocking frameworks (e.g., Google Mock) to isolate units under test from external dependencies (e.g., databases, network services, hardware). Prefer dependency injection over global state. * **Don't Do This:** Directly access external resources or rely on global state within unit tests. This makes tests slow, non-deterministic, and difficult to run in isolation. * **Why:** Mocking ensures that tests are fast, repeatable, and focus on the behavior of the unit under test. ### 2.4 CMake Integration * **Do This:** Create a separate executable target for unit tests. Use "add_test" to register the tests with CTest. Leverage "ctest_discover_tests" to automatically discover tests. * **Don't Do This:** Embed test code directly within library or application code. Manually invoke test executables. * **Why:** Separating tests allows for clean separation of concerns and enables automated test execution within the CMake build process. "ctest_discover_tests" significantly simplifies test management. """cmake # Modern CMake: Automating with "ctest_discover_tests" add_executable(MyLibraryTests test/MyLibraryTests.cpp) target_link_libraries(MyLibraryTests MyLibrary gtest_main) include(GoogleTest) gtest_discover_tests(MyLibraryTests) # Automatically find and run tests """ ## 3. Integration Testing ### 3.1 Scope * **Do This:** Focus integration tests on verifying the interactions between multiple components or modules. Aim to test the interfaces and data flows between units. * **Don't Do This:** Use integration tests to replicate unit tests (testing individual functions in isolation). * **Why:** Integration tests ensure that the parts of a system work together correctly, catching issues that unit tests might miss. ### 3.2 Environments * **Do This:** Define integration test environments with clear dependencies and configurations. Automate the setup and teardown of these environments. * **Don't Do This:** Run integration tests against production environments. Use inconsistent or manually configured environments. * **Why:** Predictable environments make integration tests reliable and repeatable. ### 3.3 Data Persistence * **Do This:** If testing code that interacts with databases or file systems, use dedicated testing databases or directories. Clear and reset the data after each test. * **Don't Do This:** Write to production databases or modify important files during testing. * **Why:** Avoid data corruption or unintended side effects on other systems. ### 3.4 CMake Integration * **Do This:** Package integration tests as separate executables. Use "add_test" to register these tests with CTest, similar to unit tests. Consider using CMake's "execute_process" command to control external processes or services during testing. * **Don't Do This:** Manually run integration tests or rely on external scripts outside of the CMake build process. * **Why:** Integrate into Continuous Integration (CI/CD) pipelines for automatic execution and reporting. """cmake # Example integration test using CMake's "execute_process" add_executable(IntegrationTests test/IntegrationTests.cpp) target_link_libraries(IntegrationTests MyLibrary) # Defines custom target to start a mock service (replace with actual service) add_custom_target(start_mock_service COMMAND ${CMAKE_COMMAND} -E echo "Starting mock service..." COMMAND ${CMAKE_COMMAND} -E sleep 1 # Simulate startup time WORKING_DIRECTORY ${CMAKE_BINARY_DIR} ) # Defines custom target to stop the mock service (replace with actual service) add_custom_target(stop_mock_service COMMAND ${CMAKE_COMMAND} -E echo "Stopping mock service..." COMMAND ${CMAKE_COMMAND} -E sleep 1 WORKING_DIRECTORY ${CMAKE_BINARY_DIR} ) # Integration test definition add_test( NAME IntegrationTest_MyFeature COMMAND ${CMAKE_COMMAND} -E env "MOCK_SERVICE_URL=http://localhost:8080" $<TARGET_FILE:IntegrationTests> WORKING_DIRECTORY ${CMAKE_BINARY_DIR} DEPENDS start_mock_service stop_mock_service #Run start and stop custom targets ) set_property(TEST IntegrationTest_MyFeature PROPERTY ENVIRONMENT "MOCK_ENABLED=1") #Example Environment var """ ## 4. End-to-End (E2E) Testing ### 4.1 Scope * **Do This:** Design E2E tests to simulate real user workflows, exercising the entire system from input to output. These tests validate that all system components work together to deliver the desired functionality. * **Don't Do This:** Focus on low-level details or internal component interactions. Treat the system as a black box. * **Why:** E2E tests provide the highest level of confidence that the system works as expected from a user's perspective. ### 4.2 Test Automation * **Do This:** Automate E2E tests using tools like Selenium, Cypress, or custom-built scripts. Integrate these tests into your CI/CD pipeline. * **Don't Do This:** Rely on manual E2E testing or sporadic, ad-hoc testing. Requires fully automated, repeatable execution. * **Why:** Automation ensures consistent and reliable E2E testing, enabling rapid feedback on changes. ### 4.3 Environment Configuration * **Do This:** Ensure the E2E test environment closely mimics the production environment, including infrastructure, configuration, and data. Consider using containerization technologies (e.g., Docker) to create consistent environments. * **Don't Do This:** Test against development or staging environments that differ significantly from production. * **Why:** Production-like environments maximize the likelihood of detecting issues before they reach users. ### 4.4 Test Data Management * **Do This:** Seed the E2E test environment with representative data to simulate real-world usage. Clean up and reset the data after each test run. * **Don't Do This:** Use minimal or unrealistic data that doesn't expose potential issues. * **Why:** Realistic data ensures the E2E tests accurately reflect the behavior of the system in production. ### 4.5 CMake Integration * **Do This:** Create CMake custom commands to manage E2E test setup, execution, and teardown. Use "add_test" to integrate these commands with CTest. Employ "execute_process" to run external test tools or scripts. * **Don't Do This:** Run E2E tests outside of the CMake build process. * **Why:** CMake integration allows for seamless E2E test execution within your build workflow. """cmake # Example E2E test using CMake and a hypothetical E2E test script add_custom_command( OUTPUT ${CMAKE_BINARY_DIR}/e2e_test_result.txt COMMAND ${CMAKE_COMMAND} -E echo "Running End-to-End Tests..." COMMAND python ${CMAKE_SOURCE_DIR}/test/e2e_tests.py --output ${CMAKE_BINARY_DIR}/e2e_test_result.txt DEPENDS MyApplication # Assuming MyApplication needs to be built first WORKING_DIRECTORY ${CMAKE_BINARY_DIR} # Set working directory correctly ) add_test(NAME EndToEndTest COMMAND ${CMAKE_COMMAND} -E true #Test always "passes", result is parsed from file. Update status appropriately. DEPENDS ${CMAKE_BINARY_DIR}/e2e_test_result.txt #Ensure Command is run. ) """ ## 5. Test Reporting and Analysis ### 5.1 CTest Integration * **Do This:** Use CTest's reporting capabilities to generate test summaries and dashboards. Configure CTest to upload test results to a CI/CD server (e.g., Jenkins, GitLab CI, GitHub Actions) or a dedicated test reporting tool (e.g., CDash). * **Don't Do This:** Ignore CTest's reporting features or rely on manual inspection of test output. * **Why:** CTest provides centralized test management and reporting, enabling you to track test results, identify trends, and quickly diagnose failures. ### 5.2 Code Coverage * **Do This:** Integrate code coverage tools (e.g., gcov, lcov) into your CMake build process. Use these tools to measure the percentage of code covered by your tests. Strive for high code coverage to minimize the risk of undetected bugs. * **Don't Do This:** Neglect code coverage analysis or assume that tests adequately cover all code paths. * **Why:** Code coverage analysis helps you identify gaps in your testing and improve the overall quality of your codebase. ### 5.3 Static Analysis * **Do This:** Integrate static analysis tools (e.g., Clang Static Analyzer, cppcheck) into your CMake build process. Use these tools to identify potential code defects, security vulnerabilities, and style violations. * **Don't Do This:** Ignore static analysis warnings or suppress them without careful consideration. * **Why:** Static analysis can detect issues early in the development cycle, before they become more costly to fix. ## 6. Avoiding Common Anti-Patterns ### 6.1 "Magic Strings" and Hardcoded Values * **Don't Do This:** Use "magic strings" or hardcoded values in test code. * **Do This:** Define constants or configuration parameters for test data, file paths, and other values. This is a common pattern. * **Why:** Improves readability and maintainability. ### 6.2 Over-Reliance on Mocks * **Don't Do This:** Mock everything. * **Do This:** Use mocks strategically to isolate units under test, but also include integration tests to verify real interactions. * **Why:** Balance unit and integration testing. ### 6.3 Ignoring Failing Tests * **Don't Do This:** Ignore failing tests or disable them without fixing the underlying issues. * **Do This:** Treat failing tests as high-priority bugs. * **Why:** Prevents test rot and ensures code quality. ### 6.4 Testing Implementation Details * **Don't Do This:** Write tests that are tightly coupled to the implementation details of the code they test. * **Do This:** Focus on testing the public interface and the expected behavior of the code. * **Why:** Reduces test fragility and makes it easier to refactor code without breaking tests.

# Performance Optimization Standards for CMake This document outlines best practices for optimizing CMake build configuration files to improve build times, reduce resource consumption, and enhance overall development workflow performance. These guidelines focus on using modern CMake features (CMake 3.15+) and avoiding common pitfalls. ## 1. Minimize Included Files and Dependencies The first principle of efficient CMake configurations is to reduce the amount of parsing and processing CMake needs to do. This primarily revolves around limiting the number of files included and keeping the dependency tree lean. ### 1.1. Reducing the Number of "include()" Calls **Do This:** Limit the number of "include()" calls. Refactor common functionality into modules that are only included when needed by specific targets. **Don't Do This:** Avoid blanket "include()" statements at the top level of your "CMakeLists.txt". This forces CMake to parse irrelevant files for every target. **Why:** Unnecessary "include()" calls introduce overhead by forcing CMake to parse and execute code that may not be relevant to the current target. **Example:** """cmake # Anti-pattern: including everything globally # include(Utilities) # Parses Utilities.cmake even if not needed # Better pattern: Target-specific inclusion function(add_my_library name) add_library(${name} ...) target_sources(${name} ...) # Only include Utilities if this target needs it. Utilies.cmake can expose # cmake functions in this scenario that are only available for targets that include it. include(Utilities OPTIONAL) if(DEFINED Utilities_FOUND) # Call Utility functions utility_function(${name}) endif() endfunction() add_my_library(MyLibrary) """ ### 1.2. Interface Libraries for Header-Only Dependencies **Do This:** Use "INTERFACE" libraries to propagate header-only dependencies and preprocessor definitions. **Don't Do This:** Copy-paste compiler flags and include directories across multiple targets. **Why:** "INTERFACE" libraries provide a clean and efficient way to manage dependencies without requiring target linking or source code compilation. This avoids unnecessary rebuilds when only header files change. **Example:** """cmake # Create an interface library for a header-only dependency add_library(MyHeaderOnlyLib INTERFACE) # Specify the include directories needed by MyHeaderOnlyLib target_include_directories(MyHeaderOnlyLib INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include> ) # Optionally, add preprocessor definitions target_compile_definitions(MyHeaderOnlyLib INTERFACE MY_HEADER_ONLY_LIB_ENABLED ) # Link against this interface library add_executable(MyExecutable main.cpp) target_link_libraries(MyExecutable PRIVATE MyHeaderOnlyLib) """ ### 1.3. Package Handling and Dependencies **Do This:** Use "find_package()" with the "CONFIG" mode and version requirements. Leverage CMake packages fully. **Don't Do This:** Manually specify include paths and library locations when a proper CMake package exists. **Why:** "find_package()" with "CONFIG" mode offloads dependency resolution to the imported package's CMake configuration files, often providing optimized build settings. This also allows cleaner cross-platform support. Modern CMake makes consumption of 3rd party libraries significantly easier using targets. **Example:** """cmake # Correct: Using find_package with required version and COMPONENTS find_package(Boost 1.70 REQUIRED COMPONENTS system filesystem) if (Boost_FOUND) add_executable(MyProgram main.cpp) target_link_libraries(MyProgram Boost::system Boost::filesystem) #Use IMPORTED targets endif() # Anti-pattern: Manual specification (prone to errors and platform-specific issues) # include_directories(/path/to/boost/include) # link_libraries(/path/to/boost/lib/libboost_system.a) """ ### 1.4 Conditional Dependencies **Do This:** Make dependencies optional and conditional using "find_package()" with the "REQUIRED" keyword omitted. Consider using components with "find_package" to minimize extraneous dependencies **Don't Do This:** Force hard dependencies when a feature can degrade gracefully without them **Why:** Reducing the number of mandatory dependencies lightens the dependency closure and improves configuration time, especially when some dependencies involve significant external processing during the CMake stage (e.g., external project inclusion or code generation). **Example:** """cmake find_package(OptionalDependency) if(OptionalDependency_FOUND) # Link to the optional dependency target_link_libraries(MyTarget PUBLIC OptionalDependency::OptionalDependency) # Note imported namespace target # ... use optional dependency features else() message(STATUS "OptionalDependency not found, some features will be disabled") # ... disable features that depend on the optional dependency target_compile_definitions(MyTarget PRIVATE "NO_OPTIONAL_DEPENDENCY") endif() """ ## 2. Optimize Compiler and Linker Flags Strategic selection and use of compiler and linker flags can drastically improve code generation, link times, and runtime performance. ### 2.1. Position Independent Executables (PIE) **Do This:** Enable Position Independent Executables (PIE) for executables, especially on modern Linux systems, and use Address Space Layout Randomization (ASLR). **Don't Do This:** Disable PIE or ASLR without a strong, justified reason. **Why:** PIE and ASLR enhance security by making it harder for attackers to exploit memory corruption vulnerabilities. **Example:** """cmake set(CMAKE_POSITION_INDEPENDENT_CODE ON) # Enable for all targets # OR, target-specific set_target_properties(MyExecutable PROPERTIES POSITION_INDEPENDENT_CODE ON ) """ ### 2.2. Link-Time Optimization (LTO) **Do This:** Enable LTO for release builds to allow the compiler to perform optimizations across translation units. **Don't Do This:** Use LTO indiscriminately for debug builds, as it can significantly increase compile times. **Why:** LTO can yield significant performance improvements by enabling inter-procedural optimizations, dead code elimination, and function inlining across the entire program. **Example:** """cmake # Enable LTO for Release builds if (CMAKE_BUILD_TYPE STREQUAL "Release") set(CMAKE_INTERPROCEDURAL_OPTIMIZATION CHECKED) #CHECKED allows user overwrite via ccmake or cmake-gui endif() """ ### 2.3. Optimize for Target Architecture **Do This:** Set compiler flags to optimize code for the target CPU architecture (e.g., "-march=native" for GCC/Clang). Use CMake generator expressions to set architecture specific flags, for example, when cross compiling. **Don't Do This:** Use generic optimization flags that don't take advantage of specific CPU features. **Why:** Architecture-specific optimizations can improve performance by utilizing instruction sets and features available on the target CPU. **Example:** """cmake if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64") target_compile_options(MyTarget PRIVATE "-march=native") # Optimize for the build machine's CPU elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm64") target_compile_options(MyTarget PRIVATE "-march=armv8-a") endif() """ ### 2.4. Precompiled Headers (PCH) **Do This:** Use precompiled headers to reduce compilation time by pre-compiling common header files. **Don't Do This:** Neglect using PCHs on large codebases with slow includes. **Why:** PCH avoids redundant compilation of frequently included headers, significantly reducing build times. **Example:** """cmake # Create a precompiled header set_source_files_properties(MyProject/pch.h PROPERTY COMPILE_LANGUAGE CXX) add_library(MyProjectPCH OBJECT MyProject/pch.h) target_compile_options(MyProjectPCH PRIVATE -x c++-header) # Adjust for your compiler # Use the precompiled header target_precompile_headers(MyTarget PUBLIC MyProject/pch.h) # Requires CMake >= 3.16 #alternative for CMake < 3.16: #target_sources(MyTarget PRIVATE MyProject/source1.cpp MyProject/source2.cpp) #set_source_files_properties( # ${CMAKE_CURRENT_SOURCE_DIR}/source1.cpp # ${CMAKE_CURRENT_SOURCE_DIR}/source2.cpp # PROPERTIES # COMPILE_FLAGS "-include pch.h" #) """ ## 3. Efficient CMake Code Structures The structure and organization of CMake code directly impact build times. Avoiding unnecessary operations and using efficient constructs reduces the configuration overhead. ### 3.1. Minimize String Operations **Do This:** Avoid extensive string manipulation within CMake scripts. For example avoid excessive generation of paths and lists. **Don't Do This:** Perform complex string processing that will be invoked on every configuration. **Why:** CMake string operations can be slow, especially when dealing with large strings or complex regexes. **Example:** """cmake # Bad: Repeated string appending/manipulation set(MY_PATH "${CMAKE_SOURCE_DIR}") set(MY_PATH "${MY_PATH}/src") set(MY_PATH "${MY_PATH}/module1") # Better: Directly construct the path if possible. set(MY_PATH "${CMAKE_SOURCE_DIR}/src/module1") """ ### 3.2. Use "set(CACHE)" Sparingly **Do This:** Only use "set(CACHE)" for variables that need to persist across CMake invocations, and use them BEFORE "project()" **Don't Do This:** Overuse "set(CACHE)", as it can slow down the configuration process. **Why:** Cache variables are re-read from disk on every CMake run, which incurs overhead. Limit their use to persistent configuration options. **Example:** """cmake # Good pattern: Defining cache variables before project() set(MY_OPTION "default_value" CACHE STRING "Description of the option") project(MyProject) # Within a function or scope within CMake set(LOCAL_VARIABLE "value") # Not cached """ ### 3.3. Efficient List Operations **Do This:** Use CMake's built-in list manipulation commands efficiently. Only iterate when necessary. **Don't Do This:** Iterate over lists unnecessarily or perform redundant list operations. **Why:** Inefficient list handling degrades CMake performance, especially on large projects with many source files or dependencies. **Example:** """cmake # Bad: Inefficient loop set(MY_FILES "file1.cpp;file2.cpp;file3.cpp") foreach(FILE ${MY_FILES}) message(STATUS "Processing ${FILE}") # Unnecessarily iterates endforeach() # Better: Process the entire list at once when possible message(STATUS "All files: ${MY_FILES}") """ ### 3.4. Variable Scoping **Do This:** Leverage variable scoping (functions, blocks) to avoid variable pollution in the global scope. **Don't Do This:** Use global variables unnecessarily, as these can lead to conflicts and unintended side effects, slowing down debugging and adding complexity. **Why:** Scoping improves code clarity, reduces the risk of name collisions, and allows CMake to manage variable lifetimes more efficiently. **Example:** """cmake function(my_function) set(local_variable "value") # Local to the function message(STATUS "Local variable: ${local_variable}") endfunction() my_function() #message(STATUS "Local variable outside function: ${local_variable}") # Error: variable not defined """ ### 3.5 Generator Expressions **Do This:** Use Generator expressions to defer complex logic to generator time. This is especially crucial if the dependency checking involves many checks. **Don't Do This:** Perform potentially costly logic evaluation during CMake configuration when the information is only needed at generate time. **Why:** Generator expressions are evaluated during build system generation, so it can evaluate system information later during generate step rather than at configuration. **Example:** """cmake add_executable(my_app main.cpp) target_compile_definitions(my_app PRIVATE "DEBUG_MODE=$<$<CONFIG:Debug>:TRUE;FALSE>" # Evaluated during compile step rather than evaluate the if statement in CMake config ) """ ## 4. Parallel Builds and Ninja Generator Embrace parallel builds and modern build systems to reduce compilation time. ### 4.1. Utilizing Parallel Compilation **Do This:** Encourage users to use the "-j" flag with "make" or specify the number of jobs in IDEs to enable parallel compilation. **Don't Do This:** Artificially limit the number of parallel jobs or fail to inform users about the benefits of parallel compilation. **Why:** Parallel compilation significantly reduces build times, especially on multi-core processors. **Example:** Instruct users to build with: "make -j$(nproc)" ### 4.2. Ninja Generator **Do This:** Use the Ninja generator, especially for large projects, as it is generally faster than the "make" generator. **Don't Do This:** Stick with the "make" generator without considering the potential performance benefits of Ninja. **Why:** Ninja is designed for speed, with a focus on incremental builds and parallel execution. It tends to outperform "make" in many scenarios. **Example:** """bash cmake -G Ninja . ninja """ ### 4.3. Ccache Integration **Do This:** Integrate "ccache" to speed up recompilation by caching compiled object files. **Don't Do This:** Ignore "ccache" in environments where frequent recompilation occurs. **Why:** "ccache" reduces build times by reusing previously compiled object files when the source code and compiler flags haven't changed. **Example:** """cmake # Add ccache to the compiler command line (requires ccache to be installed) find_program(CCACHE_PROGRAM ccache) if(CCACHE_PROGRAM) set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}") endif() """ ## 5. Modularization and Abstraction Breaking CMake configurations into logical modules simplifies maintenance and promotes reuse. ### 5.1. Custom Modules and Functions **Do This:** Refactor common build logic into reusable custom modules (".cmake" files) and functions. **Don't Do This:** Duplicate CMake code across multiple "CMakeLists.txt" files. **Why:** Modularization makes CMake configurations easier to understand, maintain, and extend and reduces parsing load to increase CMake configuration time. **Example:** """cmake # MyModule.cmake function(add_my_executable name) add_executable(${name} ${ARGN}) target_compile_features(${name} PUBLIC cxx_std_17) endfunction() # CMakeLists.txt include(MyModule) add_my_executable(MyProgram main.cpp) """ ### 5.2. Abstract Configuration Options **Do This:** Abstract complex configuration options behind simple, user-friendly variables with meaningful defaults. **Don't Do This:** Expose internal implementation details directly to the user. **Why:** Abstraction simplifies the configuration process, reduces the risk of errors, and allows you to change the underlying implementation without breaking user scripts. **Example:** """cmake # Good: Abstracted option option(ENABLE_FEATURE "Enable the super cool feature" ON) # Bad: Exposing implementation details # set(FEATURE_IMPL "internal_lib;dependency1;dependency2") # Hard to understand/maintain """ ### 5.3. Policy Management **Do This:** Explicitly set CMake policies using "cmake_policy()" to ensure consistent behavior across CMake versions and avoid deprecation warnings. **Don't Do This:** Rely on default policy settings, as these may change in future CMake versions. **Why:** Setting policies explicitly ensures that your CMake code behaves predictably and is forward-compatible. **Example:** """cmake cmake_minimum_required(VERSION 3.15) # Set the minimum required version before setting policies cmake_policy(SET CMP0077 NEW) # Example policy (use actual policy ID) """ By adhering to these coding standards, you can create CMake build configuration files that are performant, maintainable, and robust. This leads to faster build times, a smoother development workflow, and improved overall software quality. Remember to keep abreast of the latest CMake features and best practices by regularly consulting the official CMake documentation.

# Deployment and DevOps Standards for CMake This document outlines CMake coding standards focused on deployment and DevOps aspects. It provides guidelines for structuring CMake projects to facilitate robust build processes, seamless integration with CI/CD pipelines, and optimized production deployments. These standards are geared towards modern CMake practices and emphasize best practices for maintainability, performance, and security. ## 1. Build Process Standardization ### 1.1. Consistent Build Types **Standard:** Enforce consistent build types across development, testing, and production environments. * **Do This:** Use "CMAKE_BUILD_TYPE" and a consistent set of flags (e.g., "-DCMAKE_BUILD_TYPE=Release", "-DCMAKE_BUILD_TYPE=Debug") * **Don't Do This:** Hardcode compilation flags directly within "CMakeLists.txt" without considering build types. **Why:** Ensures predictable behavior and avoids discrepancies between environments. **Example:** """cmake # Set default build type if not specified if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES) set(CMAKE_BUILD_TYPE Release CACHE STRING "Choose the type of build, options are: Debug Release RelWithDebInfo MinSizeRel." FORCE) endif() # Compiler flags based on build type if(CMAKE_BUILD_TYPE STREQUAL "Debug") message(STATUS "Debug build type selected") add_compile_options(-g -O0) elseif(CMAKE_BUILD_TYPE STREQUAL "Release") message(STATUS "Release build type selected") add_compile_options(-DNDEBUG -O3) endif() """ ### 1.2. Out-of-Source Builds **Standard:** Always use out-of-source builds to prevent polluting source directories. * **Do This:** Create a separate build directory (e.g., "build", "out"). Run CMake from this directory. * **Don't Do This:** Run CMake directly in the source directory. **Why:** Keeps the source tree clean and allows for multiple independent builds with different configurations. **Example:** """bash mkdir build cd build cmake .. make """ ### 1.3. Package Management Integration **Standard:** Integrate with package managers (e.g., Conan, vcpkg) for dependency handling. * **Do This:** Use "find_package" with package manager configuration files. Consider using CMake FetchContent for simple external dependencies. * **Don't Do This:** Manually download and include dependencies directly in the source tree. **Why:** Simplifies dependency management, improves reproducibility, and enables version control of dependencies. **Example (Using FetchContent):** """cmake include(FetchContent) FetchContent_Declare( googletest GIT_REPOSITORY https://github.com/google/googletest.git GIT_TAG v1.13.0 ) # For versions of CMake older than 3.14, use FetchContent_GetProperties # instead of FetchContent_Populate FetchContent_Populate(googletest) if(NOT googletest_SOURCE_DIR) FetchContent_MakeAvailable(googletest) endif() include_directories(${googletest_SOURCE_DIR}/googletest/include) add_executable(my_tests test.cpp) target_link_libraries(my_tests GTest::gtest_main) """ ### 1.4. Minimizing External Dependencies **Standard:** Keep external dependencies to a minimum, preferring standard library features where appropriate. * **Why:** This reduces the risk of dependency conflicts, build failures, and security vulnerabilities. It also improves build times and reduces the overall complexity of the deployment process. * **Do This:** Carefully evaluate the necessity of each dependency. Consider writing small, self-contained functions to replace external libraries where feasible. * **Don't Do This:** Add dependencies without a clear justification. Assume that a dependency provides better performance or functionality without benchmarking and profiling. ## 2. CI/CD Integration ### 2.1. Configuration-as-Code **Standard:** Define build and deployment configurations in code (e.g., YAML files, shell scripts). * **Do This:** Store CI/CD configurations (e.g., ".gitlab-ci.yml", "Jenkinsfile") alongside the "CMakeLists.txt". * **Don't Do This:** Manually configure CI/CD pipelines through web interfaces. **Why:** Enables version control, auditability, and reproducibility of the entire build and deployment process. **Example (.gitlab-ci.yml):** """yaml stages: - build - test - deploy build: stage: build script: - mkdir build - cd build - cmake .. - make test: stage: test dependencies: - build script: - cd build - ./my_tests deploy: stage: deploy dependencies: - test script: - echo "Deploying application..." - # Deployment commands here only: - main """ ### 2.2. Test Automation **Standard:** Automate testing as part of the CI/CD pipeline. * **Do This:** Use "add_test" and CTest to define and run tests. * **Don't Do This:** Rely solely on manual testing. **Why:** Ensures code quality, detects regressions early, and provides confidence in deployments. **Example:** """cmake enable_testing() add_executable(my_tests test.cpp) target_link_libraries(my_tests gtest_main) include(GoogleTest) gtest_discover_tests(my_tests) #Recommended for modern CMake. Will auto-detect tests. add_test(NAME MyTest COMMAND my_tests) #Legacy method of adding tests """ ### 2.3. Artifact Management **Standard:** Manage build artifacts (e.g., executables, libraries) using version control and artifact repositories. * **Do This:** Use staging directories for artifacts, then upload to an artifact repository (e.g., Artifactory, Nexus) during CI/CD. * **Don't Do This:** Directly deploy from the build environment without versioning artifacts. **Why:** Enables rollback capabilities, provides a central location for binary sharing, and facilitates auditing. **Example (CMake for packaging):** """cmake include(InstallRequiredSystemLibraries) include(GNUInstallDirs) #Recommended modern approach for finding standard install locations install(TARGETS my_executable DESTINATION ${CMAKE_INSTALL_BINDIR}) # Use CMAKE_INSTALL_BINDIR for /usr/local/bin install(DIRECTORY assets/ DESTINATION ${CMAKE_INSTALL_DATADIR}/my_application) # Use CMAKE_INSTALL_DATADIR for /usr/local/share """ ### 2.4. Conditional Compilation for Environments **Standard:** Use conditional compilation and preprocessor directives to configure code behavior based on the target environment (development, testing, production). * **Do This:** Define macros or variables based on the environment and use them in the code. For example, use "-DDEBUG" or "-DPRODUCTION" flags passed to the compiler. * **Don't Do This:** Hardcode environment-specific configurations directly into the code without any mechanism for conditional behavior. **Why:** Allows for customized behavior like verbose logging in development or optimized performance in production. **Example:** CMakeLists.txt """cmake if (CMAKE_BUILD_TYPE STREQUAL "Debug") add_definitions(-DDEBUG) else() add_definitions(-DNDEBUG) endif() """ C++ Code: """c++ #ifdef DEBUG std::cout << "Debug message: Value = " << value << std::endl; #endif """ ## 3. Production Considerations ### 3.1. Optimization Flags **Standard:** Use appropriate optimization flags for production builds. * **Do This:** Use "-O3 -DNDEBUG" for Release builds. Profile the application and tune optimization flags accordingly. Consider using link-time optimization (LTO). * **Don't Do This:** Use "-g -O0" flags in production. **Why:** Improves performance and reduces binary size in production. **Example:** """cmake if(CMAKE_BUILD_TYPE STREQUAL "Release") add_compile_options(-O3 -DNDEBUG) endif() """ ### 3.2. Static Analysis **Standard:** Integrate static analysis tools (e.g., Clang Static Analyzer, SonarQube) into the CI/CD pipeline. * **Do This:** Run static analysis on every commit and fail the build if critical issues are found. Address findings promptly. * **Don't Do This:** Ignore static analysis warnings. **Why:** Identifies potential bugs, security vulnerabilities, and code quality issues early in the development lifecycle. Makes sure you have a clean build that's ready for production. **Example (basic clang-tidy):** """cmake find_program(CLANG_TIDY NAMES clang-tidy) if(CLANG_TIDY) set_property(SOURCE ${SOURCES} PROPERTY CXX_CLANG_TIDY "${CLANG_TIDY}") message(STATUS "clang-tidy found: ${CLANG_TIDY}") else() message(WARNING "clang-tidy not found.") endif() """ ### 3.3. Minimizing Binary Size **Standard:** Reduce the size of the final binary for production deployments. * **Do This:** Enable link-time optimization (LTO), strip debugging symbols, and use appropriate compiler flags. Remove unused code and dependencies. * **Don't Do This:** Include unnecessary debugging information or unused libraries in production binaries. **Why:** Smaller binaries can be deployed more quickly, consume less storage space, and potentially improve load times. **Example (LTO):** """cmake set(CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE) # Enables LTO for Release and RelWithDebInfo """ ### 3.4 Security Hardening **Standard:** Implement security hardening measures. * **Do This:** Enable compiler flags like "-fstack-protector-strong", "-D_FORTIFY_SOURCE=2", and use address sanitizers during testing. Regularly audit dependencies for vulnerabilities. Ensure proper user permissions. * **Don't Do This:** Deploy with default configurations and without security considerations. **Why:** Protects against common security exploits such as buffer overflows and format string vulnerabilities. **Example:** """cmake if(CMAKE_BUILD_TYPE STREQUAL "Release") add_compile_options( -fstack-protector-strong -D_FORTIFY_SOURCE=2 ) add_link_options(-Wl,-z,relro,-z,now) #Enable RELRO and NOW endif() """ ### 3.5. Resource Management **Standard:** Implement strategies for effective resource management (CPU, Memory, Disk I/O) * **Do This:** Use resource limits, profiling tools to optimize bottlenecks, and efficient data structures to minimize memory usage. Implement proper error handling and resource cleanup procedures. * **Don't Do This:** Leak resources, perform excessive I/O operations, or fail to monitor resource consumption in production. **Why:** Ensures that the application runs reliably and efficiently. Reduces risk of resource exhaustion and improves overall system stability. ## 4. Modern CMake and DevOps ### 4.1. Using Modules Effectively **Standard:** Leverage CMake's module system for code reuse and maintainability. * **Do This:** Create custom modules for common tasks and project-specific logic. Consider contributing reusable modules to the CMake community. * **Don't Do This:** Duplicate code across multiple "CMakeLists.txt" files. **Why:** Promotes modularity, reduces code duplication, and improves maintainability. **Example (Creating a custom module):** """cmake # In Modules/MyProjectHelpers.cmake function(my_custom_function target) # ... implementation ... endfunction() """ """cmake # In CMakeLists.txt include(MyProjectHelpers) my_custom_function(my_target) """ ### 4.2. Export Targets **Standard:** Use "install(TARGETS)" and "export" commands to create easily consumable packages. * **Do This:** Export targets to allow other projects to easily link against your libraries. * **Don't Do This:** Require consumers to manually find and link against dependencies. **Why:** Simplifies dependency management and promotes code reuse. **Example:** """cmake install(TARGETS my_library EXPORT my_library_export DESTINATION lib) install( EXPORT_SETTING_FILE DESTINATION lib/cmake/MyLibrary EXPORT_NAME MyLibraryTargets ) # In CMakeLists.txt of consuming project: find_package(MyLibrary REQUIRED) target_link_libraries(my_consumer MyLibrary::my_library) """ ### 4.3. Toolchain Files **Standard:** Utilize toolchain files for cross-compilation and specialized environments. * **Do This:** Create toolchain files to specify the compiler, linker, and other tools for a specific target platform. * **Don't Do This:** Hardcode compiler paths and flags directly in "CMakeLists.txt". **Why:** Enables cross-compilation and simplifies building for different target architectures. **Example (Toolchain file - my_toolchain.cmake):** """cmake set(CMAKE_SYSTEM_NAME Generic) set(CMAKE_SYSTEM_PROCESSOR arm) set(CMAKE_C_COMPILER arm-linux-gnueabi-gcc) set(CMAKE_CXX_COMPILER arm-linux-gnueabi-g++) set(CMAKE_FIND_ROOT_PATH /opt/arm-linux-gnueabi) set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER) set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY) set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY) set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY) #Usage: cmake -DCMAKE_TOOLCHAIN_FILE=my_toolchain.cmake .. """ ### 4.4. Handling Different Operating Systems **Standard:** Use CMake commands to handle differences in operating systems and compiler versions gracefully. * **Do This:** Use "if(WIN32)", "if(UNIX)", and similar checks, along with "CMAKE_CXX_COMPILER_ID", but prefer feature detection where possible. * **Don't Do This:** Use platform-specific code without proper checks. **Why:** Ensures the project can be built and deployed correctly across different environments. **Example:** """cmake if(WIN32) add_definitions(-D_WIN32) endif() if(CMAKE_CXX_COMPILER_ID MATCHES "Clang") message(STATUS "Using Clang compiler") endif() """ ## 5. Anti-Patterns and Common Mistakes ### 5.1. Over-Reliance on "execute_process" **Anti-Pattern:** Excessive use of "execute_process" for tasks that CMake can handle natively. * **Why:** Reduces portability, increases complexity, and can introduce security vulnerabilities. "execute_process" should be a last resort. * **Alternatives:** Use CMake's built-in commands for file manipulation, dependency management, and build system generation. ### 5.2. Ignoring CMAKE_EXPORT_COMPILE_COMMANDS **Anti Pattern:** Not setting "CMAKE_EXPORT_COMPILE_COMMANDS" to "TRUE". * **Why:** Prevents IDEs and code analysis tools from properly indexing code, thus hindering development effectiveness. * **Solution:** Set "set(CMAKE_EXPORT_COMPILE_COMMANDS TRUE)" to generate compilation databases to give IDEs access to flags and compile definitions necessary for proper code analytics and code completion. ### 5.3. Complex Custom Commands **Anti-Pattern:** Creating overly complex custom commands. * **Why:** They can become difficult to maintain and debug. They can severely slow down the build if executed unnecessarily. * **Solution:** Consider refactoring them into CMake functions or scripts. Use DEPENDS clauses to ensure correct execution order. ### 5.4. Neglecting Documentation **Anti-Pattern:** Lack of documentation for CMake code. * **Why:** Makes it difficult for other developers to understand and maintain the build system. * **Solution:** Add comments to explain the purpose of CMake code, especially complex logic. Use Markdown to document the project structure and build process. ### 5.5 Using "MESSAGE" for important information or warnings. * **Why:** "Message" statements work, but are not as effective as built-in methods. * **Solution:** Utilize "STATUS", "WARNING", and "FATAL_ERROR" message types to clearly communicate the severity and intent of messages. This document provides a foundational set of standards and best practices for deployment and DevOps with CMake. Following these guidelines will lead to more robust, maintainable, and secure projects. Remember to adapt these standards to your specific project requirements and technology stack.

# Code Style and Conventions Standards for CMake This document outlines the code style and conventions to be followed when writing CMake code. Adhering to these standards will improve the readability, maintainability, and consistency of our CMake scripts. These standards are designed to leverage modern CMake features and avoid common pitfalls. ## 1. Formatting Consistent code formatting is crucial for readability. CMake, while flexible, benefits greatly from a structured layout. ### 1.1 Indentation * **Do This:** Use 2 spaces for indentation. Avoid tabs. * **Why:** Consistent indentation improves readability across different editors and environments. Two spaces provide a good balance between nesting visibility and line length. """cmake if(TARGET_FOUND) message(STATUS "Found the target.") target_include_directories(${PROJECT_NAME} PUBLIC "${TARGET_INCLUDE_DIR}") endif() """ * **Don't Do This:** Use tabs or inconsistent indentation. * **Why:** Tabs can be interpreted differently by different editors, leading to inconsistent formatting. ### 1.2 Line Length * **Do This:** Limit lines to a maximum of 120 characters. * **Why:** This improves readability, especially on smaller screens. * **How:** Break long lines using parentheses for function arguments or string concatenation where appropriate. """cmake target_link_libraries( ${PROJECT_NAME} PUBLIC ${DEPENDENCY_A} ${DEPENDENCY_B} ${DEPENDENCY_C} # Keep each dependency on its own line for better readability ) set(LONG_STRING "This is a very long string that needs to be broken " "into multiple lines for readability." ) """ ### 1.3 Whitespace * **Do This:** Use whitespace to improve readability. * **Why:** Proper spacing makes the code easier to scan and understand. * **Specific Rules:** * Add a space after commas in lists. * Add a space around operators (e.g., "SET(VAR ${VALUE})", not "SET(VAR ${VALUE})"). * Add an empty line between logical blocks of code (e.g., between variable definitions and target declarations). """cmake set(CMAKE_CXX_STANDARD 17) # Space after keyword, space around value add_executable(${PROJECT_NAME} main.cpp) # Separate logical blocks with an empty line target_link_libraries(${PROJECT_NAME} PUBLIC some_library) """ * **Don't Do This:** Omit spaces or use excessive spacing. ### 1.4 Comments * **Do This:** Use comments to explain complex logic, non-obvious choices, or the "why" behind a decision. * **Why:** Comments help others (and your future self) understand the code's purpose and intent. * Use "#" for single-line comments. * Use block comments ("#[[ ... ]]") for longer explanations or to temporarily disable code blocks """cmake # This function configures the project based on the platform. function(configure_platform) if(WIN32) # Windows-specific configuration message(STATUS "Configuring for Windows") else() # Linux/macOS configuration message(STATUS "Configuring for non-Windows") endif() endfunction() #[[ This entire section is temporarily disabled for debugging. message("This message will not be printed.") #]] """ * **Don't Do This:** Write obvious comments (e.g., "# Set variable x to 5"). Over-commenting can clutter the code. Also avoid commenting out code permanently; prefer deleting it. ## 2. Naming Conventions Clear and consistent naming conventions are essential for understanding the purpose of variables, functions, and targets. ### 2.1 Variables * **Do This:** Use uppercase for variables. Use underscores to separate words. * **Why:** This makes variables easily distinguishable from CMake keywords and commands. * "PROJECT_NAME", "CMAKE_BUILD_TYPE", "MY_CUSTOM_VARIABLE" * **Scope Awareness:** * Use prefixes to indicate scope when necessary (e.g., "LOCAL_VAR" for function-local variables, "PRIVATE_VAR" for internal implementation details). * Consider using "_" prefix to indicate a variable meant to implement behavior and not exposed as public interface. """cmake function(my_function) set(LOCAL_VAR "function-local" PARENT_SCOPE) # function value accessible outside the function endfunction() set(_HIDDEN_INTERNAL_VAR "very secret") """ * **Don't Do This:** Use lowercase or mixed-case for variables. Use cryptic or single-letter variable names (except for loop iterators). ### 2.2 Functions and Macros * **Do This:** Use lowercase for the function/macro name. Use underscores to separate words. * **Why:** Improves readability and distinguishes from variables. * "configure_project", "add_custom_target" * **Don't Do This:** Use uppercase or mixed-case. ### 2.3 Targets * **Do This:** Use camelCase for target names. * **Why:** Consistency across projects. * "myExecutable", "myLibrary" * **Prefixing:** * Prefix user defined targets. * "myExecutable", "myLibrary" * Don't prefix imported targets * "Boost::boost" * **Don't Do This:** Use uppercase or inconsistent casing. ### 2.4 Properties * **Do This:** Follow the existing CMake property naming convention (uppercase, underscores). * **Why:** Consistency with built-in properties. * "CMAKE_CXX_STANDARD", "BUILD_SHARED_LIBS" * **Don't Do This:** Deviate from the standard CMake property naming convention. ## 3. Command Usage Using CMake commands effectively is crucial for writing clean and maintainable scripts. ### 3.1 Modern CMake * **Do This:** Use modern CMake features (version 3.15+). * **Why:** Modern CMake provides more expressive and maintainable ways to manage targets, dependencies, and build configurations. * **Target-Based Approach:** Prefer target-based commands like "target_include_directories", "target_link_libraries", and "target_compile_features" over global commands like "include_directories", "link_libraries", and "add_definitions". """cmake # Modern CMake (Target-based) add_library(myLibrary STATIC library.cpp) target_include_directories(myLibrary PUBLIC include) target_link_libraries(myLibrary PUBLIC dependencyA dependencyB) target_compile_features(myLibrary PUBLIC cxx_std_17) # Add standards to target """ """cmake # Legacy CMake (Avoid) add_library(myLibrary STATIC library.cpp) include_directories(include) link_libraries(dependencyA dependencyB) set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17") #Set compiler flags for all targets. """ * **Interface Libraries** Use interface libraries to propagate properties to dependents. """cmake add_library(MyLib INTERFACE) target_include_directories(MyLib INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/include) target_compile_definitions(MyLib INTERFACE DEBUG_MODE) add_library(MyCode code.cpp) target_link_libraries(MyCode MyLib) # MyCode now has include directories and compile defines """ * **Don't Do This:** Use deprecated commands or variables. Rely on global state or side effects. Avoid mixing modern and legacy approaches. ### 3.2 Conditionals * **Do This:** Use "if()", "elseif()", and "else()" for conditional logic. Use "if(DEFINED ...)" or "if(NOT DEFINED ...)" to check if a variable is defined. Use comparison operators for string or numerical comparisons. Use "if(TARGET ...)" to check if a target exists. """cmake if(CMAKE_BUILD_TYPE STREQUAL "Debug") message(STATUS "Debug mode is enabled") elseif(CMAKE_BUILD_TYPE STREQUAL "Release") message(STATUS "Release mode is enabled") else() message(STATUS "Unknown build type") endif() if(TARGET myTarget) message(STATUS "Target myTarget exists") endif() """ * **Don't Do This:** Use deprecated conditional constructs (e.g., "IF(DEFINED ...)" - case-insensitive, error-prone). Use string comparisons for numerical values (CMake variables are weakly typed). ### 3.3 Loops * **Do This:** Use "foreach()" loops for iterating over lists. Use "while()" loops for more complex conditional iteration. """cmake set(MY_LIST "item1" "item2" "item3") foreach(ITEM IN LISTS MY_LIST) message(STATUS "Processing item: ${ITEM}") endforeach() set(COUNTER 0) while(COUNTER LESS 5) math(EXPR COUNTER "${COUNTER} + 1") message(STATUS "Counter: ${COUNTER}") endwhile() """ * **Don't Do This:** Use manual index manipulation within loops. Overuse or misuse "while()" loops. ### 3.4 Functions and Macros (Revisited) * **Do This:** Use functions for logical groupings of CMake commands that need to be reused with different arguments. Use macros for code fragments that need to be textually substituted into the calling scope (less common in modern CMake). """cmake # Function example function(add_source_files TARGET_NAME SOURCE_DIR) file(GLOB_RECURSE SOURCES "${SOURCE_DIR}/*.cpp") target_sources(${TARGET_NAME} PRIVATE ${SOURCES}) endfunction() # Call the function add_source_files(myExecutable src) # Macro example (use sparingly) macro(print_message MESSAGE) message(STATUS "${MESSAGE}") endmacro() # Call the macro print_message("Hello from a macro!") """ * **Don't Do This:** Use macros excessively (functions are generally preferred). Create functions or macros with side effects outside of their intended scope. ## 4. Project Structure A well-defined project structure makes CMake scripts easier to navigate and maintain. ### 4.1 Source Code Organization * **Do This:** Organize source code into logical directories (e.g., "src", "include", "test"). * **CMake Organization:** Mirror the source code structure in your CMake project. * Use "add_subdirectory()" to include CMakeLists.txt files in subdirectories. * Benefits: Enhanced encapsulation, separation of concerns, and improved modularity. """ project/ ├── CMakeLists.txt ├── src/ │ ├── CMakeLists.txt │ ├── main.cpp │ └── ... ├── include/ │ ├── mylib/ │ │ ├── header1.h │ │ └── header2.h │ └── ... └── test/ ├── CMakeLists.txt └── ... """ **"project/CMakeLists.txt":** """cmake cmake_minimum_required(VERSION 3.15) project(MyProject) add_subdirectory(src) add_subdirectory(test) """ **"project/src/CMakeLists.txt":** """cmake add_library(MyLibrary STATIC main.cpp) target_include_directories(MyLibrary PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/../include) """ * **Don't Do This:** Place all source files in a single directory. Create overly deep or complex directory structures. ### 4.2 Modules * **Do This:** Create reusable CMake modules for common tasks (e.g., finding dependencies, setting compiler flags). * Store modules in a dedicated directory (e.g., "cmake/Modules"). * Use the "CMAKE_MODULE_PATH" variable to tell CMake where to find your modules. **"cmake/Modules/FindMyDependency.cmake":** """cmake # Module to find MyDependency find_path( MYDEPENDENCY_INCLUDE_DIR NAMES mydependency.h PATHS /opt/mydependency/include ) if(MYDEPENDENCY_INCLUDE_DIR) set(MYDEPENDENCY_FOUND TRUE) else() set(MYDEPENDENCY_FOUND FALSE) endif() if(MYDEPENDENCY_FOUND) message(STATUS "Found MyDependency") else() message(WARNING "MyDependency not found") endif() mark_as_advanced(MYDEPENDENCY_INCLUDE_DIR) """ **"CMakeLists.txt":** """cmake list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/Modules") include(FindMyDependency) if(MYDEPENDENCY_FOUND) include_directories(${MYDEPENDENCY_INCLUDE_DIR}) # ... rest of the logic ... endif() """ * **Don't Do This:** Duplicate code across multiple CMakeLists.txt files. Fail to properly document custom modules. ### 4.3 Dependencies * **Do This:** Use "find_package()" to locate external dependencies. Use imported targets provided by "find_package()" to link against dependencies. Modern CMake strongly encourages the use of imported targets for dependency management. """cmake # Find the Boost library find_package(Boost REQUIRED COMPONENTS system filesystem) # Link against Boost (using imported target) if(Boost_FOUND) target_link_libraries(myExecutable PUBLIC Boost::system Boost::filesystem) #Use target based linking endif() """ * **Don't Do This:** Manually specify include directories and library paths for external dependencies. Use hardcoded paths. ## 5. Error Handling Robust error handling is essential for preventing unexpected build failures. ### 5.1 Checks and Assertions * **Do This:** Use "if()" statements to check for potential errors (e.g., missing files, invalid arguments). Use "message(FATAL_ERROR ...)" to abort the build if a critical error is encountered. Use "assert()" (if enabled, see below) for internal consistency checks. * **ASSERTIONS:** * Turning on Assertions: In your root CMakeLists.txt file, add the following line: """cmake set(CMAKE_BUILD_TYPE Debug) #Ensure Debug build type. """ * Example Usage of Assertions: """cmake # Check that a target exists if (NOT TARGET MyTarget) message(FATAL_ERROR "Target MyTarget does not exist.") endif() """ ### 5.2 Warnings * **Do This:** Use "message(WARNING ...)" to report non-critical issues to the user. """cmake if(NOT DEFINED MY_VARIABLE) message(WARNING "MY_VARIABLE is not defined. Using default value.") set(MY_VARIABLE "default") endif() """ * **Don't Do This:** Ignore potential errors or warnings. Suppress warnings without understanding their cause. ## 6. Build Configuration Proper build configuration ensures that the project can be built correctly in different environments. ### 6.1 Build Types * **Do This:** Use "CMAKE_BUILD_TYPE" to control the build type (e.g., Debug, Release). Set appropriate compiler flags based on the build type. * Users can set build type at configuration time "cmake -DCMAKE_BUILD_TYPE=Release .." """cmake if(CMAKE_BUILD_TYPE STREQUAL "Debug") target_compile_definitions(myExecutable PRIVATE DEBUG_MODE) # Enable debug mode endif() """ * **Don't Do This:** Hardcode build-type-specific logic in the CMakeLists.txt file. ### 6.2 Compiler Flags * **Do This:** Use "target_compile_options()" to set compiler flags for specific targets. Use "CMAKE_CXX_STANDARD" to set the C++ standard. * Prefer "target_compile_features" for more modern standards. """cmake set(CMAKE_CXX_STANDARD 17) # Set the C++ standard set(CMAKE_CXX_STANDARD_REQUIRED ON) # Require the C++ standard target_compile_options(myExecutable PRIVATE -Wall -Wextra) # Add warning flags """ * **Don't Do This:** Modify "CMAKE_CXX_FLAGS" directly (use "target_compile_options" instead). Use incompatible or deprecated compiler flags. ## 7. Platform Specific Code * **Do This:** Utilize CMake's built-in variables to determine the target platform and adjust build settings accordingly. """cmake if(WIN32) # Windows-specific settings message(STATUS "Configuring for Windows") target_compile_definitions(MyTarget PRIVATE WIN32_LEAN_AND_MEAN) # Define a macro for Windows builds elseif(UNIX) # Unix-like settings message(STATUS "Configuring for Unix") endif() """ * **Don't Do This:** Rely on environment variables or external tools to detect the platform. This reduces portability. ## 8. Security Considerations * **Do This:** Avoid executing arbitrary commands or scripts during the CMake configuration process. Be cautious when using "execute_process", and always validate inputs. Use secure coding practices in your C++ code to prevent vulnerabilities. * **Don't Do This:** Embed sensitive information (e.g., passwords, API keys) directly in CMakeLists.txt files. ## 9. Continuous Integration * **Do This:** Integrate CMake into your continuous integration (CI) system. Use a consistent build environment across all CI builds. Run unit tests as part of the CI process. * **Don't Do This:** Rely on manual builds for testing. Use different build environments for development and CI. By adhering to these code style and conventions, we can ensure that our CMake scripts are readable, maintainable, and robust. This will improve collaboration, reduce errors, and ultimately lead to higher-quality software.

# Component Design Standards for CMake This document outlines coding standards specifically for component design in CMake. The focus is on creating reusable, maintainable, and scalable CMake code using modern practices, targeting the latest CMake version. ## 1. Introduction to CMake Component Design Component design in CMake involves organizing code into modular, independent units that can be reused across different projects or within the same project. This promotes code reuse, reduces redundancy, improves maintainability, and simplifies collaboration. * **Goals:** Promote modularity, reusability, maintainability, and collaboration. * **Focus:** Defining, organizing, and using components in CMake projects. ## 2. Architectural Considerations ### 2.1 Define Component Boundaries Clearly * **Do This:** Define clear interfaces and responsibilities for each component. A component should have a well-defined purpose and should encapsulate a specific set of functionality. * **Don't Do This:** Create components with overlapping responsibilities or poorly defined interfaces. Avoid "god modules" that try to do everything. **Why:** Clear boundaries simplify understanding, testing, and maintenance. Well-defined interfaces reduce coupling and make components easier to reuse. **Example:** """cmake # my_component/CMakeLists.txt cmake_minimum_required(VERSION 3.20) # Example version declaration project(MyComponent) # Define the interface target add_library(MyComponent INTERFACE) # Include directories for the component's public headers target_include_directories(MyComponent INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include> ) # Define properties of the INTERFACE target - these will be inherited # by any target that *links* to this one. Consider IMPORTED_CONFIGURATIONS # if different exported configurations need different values. set_property(TARGET MyComponent PROPERTY INTERFACE_COMPILE_DEFINITIONS "MY_COMPONENT_ENABLED") # Install the component's headers (public interface!) install(DIRECTORY include/ DESTINATION include COMPONENT MyComponent) # Use a component name # Export the target for use in other projects (if you intend for this to be consumed by other projects) install(TARGETS MyComponent EXPORT MyComponentTargets NAMESPACE MyNamespace:: DESTINATION lib/cmake/MyComponent COMPONENT MyComponent) # Create export set for packaging export(TARGETS MyComponent FILE "${CMAKE_CURRENT_BINARY_DIR}/MyComponentTargets.cmake") include(CMakePackageConfigHelpers) write_basic_package_version_file( "${CMAKE_CURRENT_BINARY_DIR}/MyComponentConfigVersion.cmake" VERSION "${PROJECT_VERSION}" COMPATIBILITY SameMajorVersion ) # Generate the config file configure_package_config_file( "${CMAKE_CURRENT_SOURCE_DIR}/MyComponentConfig.cmake.in" # Make sure this file exists! "${CMAKE_CURRENT_BINARY_DIR}/MyComponentConfig.cmake" INSTALL_DESTINATION "lib/cmake/MyComponent" ) install(FILES "${CMAKE_CURRENT_BINARY_DIR}/MyComponentConfig.cmake" "${CMAKE_CURRENT_BINARY_DIR}/MyComponentConfigVersion.cmake" DESTINATION lib/cmake/MyComponent COMPONENT MyComponent ) """ """cmake # my_component/include/my_component/my_component.h #ifndef MY_COMPONENT_MY_COMPONENT_H #define MY_COMPONENT_MY_COMPONENT_H #ifdef MY_COMPONENT_ENABLED #define MY_COMPONENT_API __declspec(dllexport) // Or equivalent for other platforms #else #define MY_COMPONENT_API __declspec(dllimport) #endif namespace MyNamespace { class MY_COMPONENT_API MyComponentClass { public: MyComponentClass(); int doSomething(); }; } // namespace MyNamespace #endif // MY_COMPONENT_MY_COMPONENT_H """ """cmake # my_component/MyComponentConfig.cmake.in # Defines the interface to the MyComponent library. include(${CMAKE_CURRENT_LIST_DIR}/MyComponentTargets.cmake) # Helper function for finding all the dependencies. include(FindPackageHandleStandardArgs) find_package_handle_standard_args(MyComponent REQUIRED_VARS MyComponent_FOUND VERSION_VAR MyComponent_VERSION ) mark_as_advanced(MyComponent_FOUND MyComponent_VERSION) """ **Anti-Pattern:** Creating a single, monolithic CMakeLists.txt file that manages the entire project. ### 2.2 Prioritize Interface Targets * **Do This:** Use "INTERFACE" libraries to define the public API of a component. Interface libraries act as a contract, defining the include directories, compile definitions, and link dependencies required to use the component. Crucially, they do not contribute any code themselves, they are pure metadata. * **Don't Do This:** Directly expose implementation details or internal headers through global CMake variables. Avoid directly manipulating compiler flags or linker settings outside the component's CMakeLists.txt. **Why:** Interface libraries provide a clean, explicit way to define the component's public API. They improve encapsulation and reduce the risk of conflicts between components. **Example:** """cmake # my_component/CMakeLists.txt (as shown above in 2.1 example) add_library(MyComponent INTERFACE) target_include_directories(MyComponent INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include> # Install-time path to headers ) target_compile_definitions(MyComponent INTERFACE "MY_COMPONENT_ENABLED" # Defined when using the component ) # Example of requiring a dependency. Better to call find_package() in the CONSUMING project # target_link_libraries(MyComponent INTERFACE AnotherComponent) """ **Anti-Pattern:** Making assumptions about the consuming project's environment or compiler settings. ### 2.3 Use Namespaces to Prevent Collisions * **Do This:** Encapsulate components within namespaces to avoid naming conflicts. Use a consistent naming scheme for targets, variables, and functions. * **Don't Do This:** Use global, unqualified names that may clash with other components or libraries. **Why:** Namespaces provide a clear separation between components and prevent accidental naming conflicts. **Example:** """cmake # my_component/CMakeLists.txt add_library(MyNamespace::MyComponent INTERFACE) # Namespaced target set_target_properties(MyNamespace::MyComponent PROPERTIES EXPORT_NAME MyComponent) # For older versions """ In C++: """c++ // my_component/include/my_component/my_component.h namespace MyNamespace { class MyComponentClass { // ... }; } // namespace MyNamespace """ **Anti-Pattern:** Using short, generic names like "LIB" or "UTIL" for targets or variables. ### 2.4 Package Components for Distribution * **Do This:** Use "install()" and "export()" commands to package components for distribution. Create a CMake package configuration file (e.g., "MyComponentConfig.cmake") that defines how to use the component in other projects. * **Don't Do This:** Manually copy header files or libraries. Rely on consuming projects to find dependencies or configure compiler settings. **Why:** Packaging ensures that components can be easily integrated into other projects without requiring manual configuration or dependency management. **Example:** """cmake # my_component/CMakeLists.txt (as shown above in 2.1 example) install(TARGETS MyComponent EXPORT MyComponentTargets NAMESPACE MyNamespace:: DESTINATION lib/cmake/MyComponent COMPONENT MyComponent) export(TARGETS MyComponent FILE "${CMAKE_CURRENT_BINARY_DIR}/MyComponentTargets.cmake") """ **Anti-Pattern:** Requiring users to manually set CMake variables or modify their build scripts to use a component. ## 3. Implementation Details ### 3.1 Use Target Properties * **Do This:** Use "target_include_directories", "target_compile_definitions", and "target_link_libraries" to configure target properties. Avoid using global variables or directly setting compiler flags. Use generator expressions for conditional configuration. * **Don't Do This:** Use "include_directories", "add_definitions", or "link_directories" commands, as these affect the entire project rather than specific targets. **Why:** Target properties provide a localized and explicit way to configure targets. This reduces the risk of unintended side effects and makes it easier to understand the dependencies of each target. **Example:** """cmake # my_component/CMakeLists.txt add_library(MyComponent STATIC src/my_component.cpp) target_include_directories(MyComponent PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include> ) target_compile_definitions(MyComponent PUBLIC "MY_COMPONENT_ENABLED" ) target_link_libraries(MyComponent PUBLIC AnotherComponent # Assuming you have another component defined ) """ **Anti-Pattern:** Adding include directories or compile definitions to the global scope. ### 3.2 Leverage Generator Expressions * **Do This:** Use generator expressions ("$<...>", "$<$CONFIG:...>") to conditionally configure targets based on the build environment. * **Don't Do This:** Rely on manual checks or conditional logic within CMakeLists.txt files. **Why:** Generator expressions allow you to define build-time conditions without modifying the CMakeLists.txt file. This improves flexibility and simplifies cross-platform builds. **Example:** """cmake # my_component/CMakeLists.txt target_compile_definitions(MyComponent PRIVATE "$<$<CONFIG:Debug>:DEBUG_MODE>" # Only define DEBUG_MODE in Debug configuration ) target_link_libraries(MyComponent PRIVATE "$<$<PLATFORM_ID:Windows>:some_windows_lib>" ) """ **Anti-Pattern:** Using "if()" statements with "CMAKE_BUILD_TYPE" or other global variables to configure targets. ### 3.3 Encapsulate Implementation Details * **Do This:** Hide implementation details within the component. Expose only the necessary headers and libraries through the public API. Use the "PRIVATE" and "INTERFACE" keywords to control visibility. * **Don't Do This:** Expose internal headers or implementation details through the public API. **Why:** Encapsulation protects the component from changes to its implementation and reduces the risk of breaking compatibility with other components. **Example:** """cmake # my_component/CMakeLists.txt add_library(MyComponent STATIC src/my_component.cpp src/internal_implementation.cpp) target_include_directories(MyComponent PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include> PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/src/internal # Don't expose this! ) """ In C++: """c++ // my_component/src/internal_implementation.cpp #include "internal_implementation.h" // Not exposed in public headers """ **Anti-Pattern:** Including internal headers in the component's public API. ### 3.4 Manage Dependencies Explicitly * **Do This:** Use "find_package()" to locate external dependencies. Use "target_link_libraries()" to link against the required libraries. Specify minimum version requirements. Ensure dependencies are installed as part of continuous integration. * **Don't Do This:** Assume that dependencies are already installed or located in a specific directory. Rely on global variables or manual configuration to find dependencies. **Why:** Explicit dependency management ensures that the component can be built and used in different environments. It avoids version conflicts and simplifies dependency resolution. **Example:** """cmake # my_component/CMakeLists.txt find_package(Boost 1.70 REQUIRED COMPONENTS system filesystem) # Specify minimum version if (Boost_FOUND) target_include_directories(MyComponent PUBLIC ${Boost_INCLUDE_DIRS} ) target_link_libraries(MyComponent PUBLIC Boost::system # Modern target-based linking ) else() message(FATAL_ERROR "Boost library not found.") endif() """ **Anti-Pattern:** Directly linking to system libraries without using "find_package()". For example, hardcoding "/usr/lib/libcurl.so". ## 4. Advanced Techniques ### 4.1 Custom Commands and Targets * **Do This:** Use custom commands and custom targets to automate build-time tasks. Wrap complex logic into functions for reusability. * **Don't Do This:** Perform manual steps or rely on external scripts to execute build-time tasks. **Why:** Custom commands and targets enable you to integrate external tools and processes into the build system. They improve automation and reduce the risk of human error. **Example:** """cmake # my_component/CMakeLists.txt add_custom_command( OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/generated_file.txt COMMAND ${CMAKE_COMMAND} -E echo "Hello, world!" > ${CMAKE_CURRENT_BINARY_DIR}/generated_file.txt DEPENDS src/input_file.txt # Re-run if input file changes ) add_custom_target(GenerateFile DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/generated_file.txt ) add_dependencies(MyComponent GenerateFile) # Ensure file is generated before building component """ **Anti-Pattern:** Running external scripts directly from the command line or relying on manual configuration steps. ### 4.2 Abstract Factories and Plugin Architectures (Conceptual, not CMake syntax) Modern C++ component design often leverages patterns like abstract factories to choose implementations at runtime. These components can be dynamically loaded as plugins. While CMake does not directly implement these patterns, it provides the build infrastructure. * "add_library(... MODULE)" creates a dynamically loadable module. * Configure include paths to abstract interfaces to allow code to be compiled independently from specific plug-ins. * Use "install()" commands to copy modules to a plugin directory with a well-defined structure. * Write CMake code to discover plugins at runtime (using "glob()" or similar). ### 4.3 Testing and Continuous Integration * **Do This:** Integrate unit tests and integration tests into the build process. Use a testing framework like Catch2 or Google Test. Set up continuous integration to automatically build and test the component on different platforms. Use code coverage tools to measure the test coverage. **Why:** Testing ensures that the component is working correctly and that changes do not introduce regressions. Continuous integration automates the build and testing process and provides early feedback on potential problems. **Example:** """cmake # my_component/CMakeLists.txt enable_testing() add_executable(MyComponentTests test/my_component_tests.cpp) target_link_libraries(MyComponentTests MyComponent) include(GoogleTest) gtest_discover_tests(MyComponentTests) """ **Anti-Pattern:** Skipping unit tests or relying on manual testing to verify the correctness of the component. Failing to regularly build the component with a continuous build system. ## 5. Conclusion By adhering to these component design standards, you can create reusable, maintainable, and scalable CMake code. This will improve collaboration, reduce redundancy, and simplify the development process. Remember to leverage the latest CMake features and best practices to ensure that your code is modern and efficient. This document will be continually updated as new CMake features and best practices emerge. Consult official CMake documentation and release notes regularly.