[CMake] External project source

[Nicholas Yue]

On 13/02/12 6:47 PM, Eric Noulard wrote:
> 2012/2/13 Nicholas Yue<yue.nicholas at gmail.com>:
>> Hi,
>>
>>     There is an existing project I have access to that already have CMake
>> configuration file but the way it is written requires alot of preprocessing
>> steps (python, shell etc) before it is usable.
>>
>>     I wanted to investigate a cleaner (truer to CMake original design
>> purpose) usage of CMake,
>>
>>     So, I have an  original-project directory which contains both the source
>> and the CMakeLists.txt in a nested directory structure.
>>
>>     I want to create my own CMake hierarchy (structure the same way) but
>> reference the source code in the original-project directory location.
>>
>>     How do I tell CMake to refer to source code at some other top level
>> directory as a starting point.
>>
>>     Is there such a concept in CMake ?
> I am not sure to fully understand you request but in a CMakeLists.txt
> you can perfectly
> refer to source located outside the directory the CMakeLists.txt is in,
> you can use either relative or absolute path and do something like:
>
> add_executable(NiceTarget ../../relpath/to/source.c
> ${CMAKE_SOURCE_DIR}/abspath/to/another.c)
Yes, I know I can do that. I am hoping to avoid maintaining a hierarchy 
of such modification.

There are 42 CMakeLists.txt files each with multiple libraries, test and 
such.

I was hoping there is a way to (assuming I maintain the same hierarchy) 
tell CMake to start looking for source from some other top level 
directory 'once' and it will be able to find the source in the 'other' 
location that is different to my 'cleaned-up' version of CMakeLists.txt

Regards

> this is usually a bad idea but this should work.
>
> Now that said if you do that for compatibility purpose in order to
> maintain the legacy build
> before doing the switch to "genuine" CMake build then may be using a
> VCS like git would
> be a better way to go.
I have this as a fall back.

Best regards