What Is the $Origin Token In Cmake?

The $origin token in CMake is a special variable that represents the directory containing the CMakeLists.txt file that is currently being processed. This token can be used in CMake scripts to refer to files or directories relative to the location of the CMakeLists.txt file. By using the $origin token, developers can easily reference files or directories that are located in the same directory as the CMakeLists.txt file without hardcoding absolute paths. This makes CMake scripts more portable and maintainable.

What is the syntax for using the $origin token in CMake?

The syntax for using the $origin token in CMake is as follows:

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$<TARGET_FILE_DIR:target>/$<TARGET_FILE_NAME:target>

This token is typically used to get the directory of the target file (executable or library) of the specified target in a CMake project.

How can the $origin token help in resolving file paths in CMake?

The $origin token in CMake can help in resolving file paths by providing the location of the file in which it is defined. This can be useful when working with relative paths or when referencing files from different directories. By using the $origin token, CMake can determine the correct path to the file and resolve any relative paths accordingly. This can help to ensure that files are referenced correctly and that the build process runs smoothly.

How to streamline the usage of the $origin token in large CMake projects?

One way to streamline the usage of the $origin token in large CMake projects is to create a CMake function or macro that handles the tokenization and path manipulation for you. This function or macro can be used throughout the project in place of manually using the $origin token.

Here is an example of how you could create a CMake function to handle the $origin token:

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# Define a function to handle $origin token
function(get_absolute_path OUTPUT_VARIABLE RELATIVE_PATH)
    set(ABSOLUTE_PATH ${CMAKE_CURRENT_LIST_DIR}/${RELATIVE_PATH})
    set(${OUTPUT_VARIABLE} ${ABSOLUTE_PATH} PARENT_SCOPE)
endfunction()

You can then use this function in your CMake scripts like this:

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get_absolute_path(ABSOLUTE_SRC_DIR src)
get_absolute_path(ABSOLUTE_INCLUDE_DIR include)

This way, you can easily get the absolute paths of your source and include directories without having to manually manipulate the paths using the $origin token.

Additionally, you could consider organizing your project structure in a way that minimizes the need for the $origin token in the first place. For example, you could set up your project directories in a standardized way so that the relative paths are consistent across different parts of your project. This can help reduce the complexity of your CMake scripts and make them easier to maintain.

Overall, using a function or macro to handle the $origin token and organizing your project structure in a consistent way can help streamline the usage of the $origin token in large CMake projects.