Question

I have a numeric vector implementation in C; the whole implementation is based on TYPE and then i do s/TYPE/double/g to get an implementation for double and s/TYPE/int/ to get an implementation for int. Up until now I have based the filtering on a tiny sed script which is referenced with an add_custom_command() from the CMakeLists.txt file. That has worked fine on linux, but when trying to generate a Visual Studio solution it fails (in Visual Studio).

Since the process I am performing (search-replace in a file and store the output as a new file) is so simple I thought maybe this could be achieved with builtin CMake commands?

Joakim

Answer 1

In pure cmake you have at least 3 ways to go:

1) configure_file command

• is useful for simple replaces, when you only need to substitute some placeholders within the template file based on current project configuration;
• cmake will automatically generate dependency on template file and will regenerate your file on template changes.

2) It is possible to use FILE READ or FILE STRINGS and FILE WRITE commands to make any transformation during the cmake configure step.

• any custom transformation is possible

But

• harder to maintain;
• worth cmake performance;
• no automatic monitoring for template file changes.

3) If it absolutely necessary to generate this file during the build, then you can use cmake in process script mode (cmake -P) with add_custom_command:

add_custom_command(OUTPUT vector.c
                   COMMAND $(CMAKE_COMMAND) -DTEMPLATE:STRING=vector.template -P genscript.cmake
                   DEPENDS vector.template genscript.cmake)

Where genscript.cmake is helper script you need to write. It should generate vector.c with 1) or 2) approach listened above.