cmake external project properties list

Question

I use ExternalProject_Add command in my CMakeLists.txt for adding some external project. I'd like to retrieve some project properties (exactly I'd like to get preprocessor definitions like <project>_DEFINITIONS from Find<package>.cmake).

Is there any way to get all allowed project properties for using as ExternalProject_Get_property command parameter? For example, I know about source_dir and binary_dir, i. e. something like this:

ExternalProject_Get_property(<my project> binary_dir)

OR is there any way to use find_package function immediately after dowloading external project? I definitely know that find_package for this project works after launching build (i. e. after external project is already configured). It automatically sets all necessary variables (like <project>_DEFINITIONS), but obviously find_package(<project>) is not available initially (i. e. before external project was configured).

Answer 1

When you download external package, you have only its sources. CMake has no common way for extract information about the package using only its sources.

Only sources:

Function ExternalProject_Get_property returns properties which are set by ExternalProject_Add call itself. The external project hasn't even configured at this call, so you cannot get any information about the package.

Configured:

There is command export, which allows for configured external package to publish information about some of its targets.

Installed:

Command find_package requires (normally) the package to be already installed.