[CMake] Howto to work with variables from central makefiles....

[Thomas Lehmann]

> > for an automatically forced include I have provided an
> >
> > option like this:
> >
> >
> >
> > set(WIN32_SPEC
> ${CMAKE_CURRENT_SOURCE_DIR}/../../libs/global/win32_spec.h)
>
> May you could use an absolute reference using
>
> ${PROJECT_SOURCE_DIR}/libs/global/win32_spec.h
>
> if your project is name TOTO
> (from the PROJECT(TOTO CXX) statement)
> you use
>
> ${TOTO_SOURCE_DIR}/libs/global/win32_spec.h.

it depends on how I use cmake. I can use the root of all
sources or I use a subtree.
Let's say I have following setup.

/src/libs
/src/cmake
/src/apps

when I call "cmake /src" or "cmake /src/apps" is relating the
application to be build no difference but the variable CMAKE_SOURCE_DIR
will change. My central files are in /src/cmake.

I would like avoiding to redefine search paths and variables in each individual
makefile depending on its location in the source tree. One example:

<code>
# ensuring that packages are found
set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH}
                      ${CMAKE_CURRENT_SOURCE_DIR}/../../scripts/make)

# most common definitions, macros, ... required by most projects
find_package(AllOptions)
</code>

I think that the problem is that cmake does not know where the real root
is. I have not found something except adjusting an environment variable
but this is something I would like to avoid when possible...

Thomas



>
> >
> > add_definitions(-FI ${WIN32_SPEC})
> >
> >
> > But when including this central file (find_package) the variable
> CMAKE_CURRENT_SOURCE_DIR
> > changes and then the path and filename of the header is wrong.
> >
> >
> >
> > How to proceed best?
> > Can I avoid that for those "set" statement the variable is not
> overwritten by those
> > files including this central makefile?
>
> You may use a CACHED variable
> set(WIN32_SPEC ${PROJECT_SOURCE_DIR}/libs/global/win32_spec.h CACHE
> FILEPATH "Central Include")
>
> the first calling this will set the value then other set will be
> ignored.
> If you want to override a CACHE var value you'll have to use FORCE set
> option.
>
>
>
> --
> Erk
> Membre de l'April - « promouvoir et défendre le logiciel libre » -
> http://www.april.org

Thomas Lehmann
Scrum Master

RTS Realtime Systems Software GmbH, Rembrandtstrasse 13, D-60596 Frankfurt am Main
T: +49.69.61009.0 / F: +49.69.61009.181

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