Conditional Component Inclusion Example

This example demonstrates how to conditionally include components at build time using Build System v2's pure CMake approach. Components are included or excluded based on Kconfig configuration options, and all components are written using standard CMake functions rather than IDF-specific abstractions.

Overview

In Build System v2, components can be written as plain CMake static libraries using add_library, target_link_libraries, and target_include_directories. A component is brought into the build on demand by calling idf_component_include(), which sets up the component's target name and invokes its CMakeLists.txt. Dependencies on other components are expressed using the idf::<name> alias targets.

This example uses that mechanism to conditionally pull in two utility components — logging_util and math_util — from within the main component, based on Kconfig options.

Project Structure

The project is initialized manually with idf_project_init() and idf_build_executable(), which gives precise control over which components are seeded into the build. The main component itself is a pure CMake static library. It conditionally includes logging_util and/or math_util at configure time by calling idf_component_include() inside if(CONFIG_...) guards and linking the resulting targets with target_link_libraries.

logging_util depends on IDF's log component for ESP_LOG* macros. It pulls log into the build with idf_component_include(log) and links it via the idf::log alias target. math_util has no IDF dependencies and is a self-contained static library.

Configuration Options

Two Kconfig options control which components are included:

• CONFIG_EXAMPLE_ENABLE_LOGGING — includes and links the logging_util component.
• CONFIG_EXAMPLE_ENABLE_MATH — includes and links the math_util component.

Both default to enabled. Toggle them via menuconfig under Conditional Component Example Configuration.

Building

cd examples/build_system/cmakev2/conditional_component
idf.py set-target <target>
idf.py build

To change which components are included, run idf.py menuconfig before rebuilding.

Output

With both components enabled the serial output shows info and warning log messages from logging_util and the results of add, subtract, and multiply operations from math_util. Disabling either option removes the corresponding section and replaces it with a "DISABLED" message.