[CMake] How to read and compile dynamically-generated list of cpp files

[gimmeamilk gimmeamilk]

Hi all,

I have a custom tool that processes a given list of IDL files and
produces a number of .cpp and .h files as output. I want to add those
files to the list of things to compile in my CMakeLists, and also
model the dependencies those files have on the IDL. To keep things
simple, I will state that any change to any of the IDL files should
trigger a regeneration of all cpp/h.

I have a custom command that takes care of running the generator tool
and listing all the IDL files as dependencies.

My issue is getting the subsequent list of cpp/h files into cmake at
build-time. It is not possible to infer from the name of the IDL files
what cpp files will be generated. My generator tool will, however,
output the list of generated files to a text file.

So my question is: how do I instruct cmake to "read from this text
file and add the contents as extra source and header files to be
compiled", also bearing in mind that the said text file only exists
during a certain point of the build?

Many thanks