> -----Original Message-----
> From: Joerg Bruehe [mailto:joerg.bruehe@stripped]
> Sent: Freitag, 4. Februar 2011 12:23
> To: Guilhem Bichot
> Cc: commits
> Subject: Re: review of bug#42969
>
> Hello Guilhem,
> Probably, that is the result of "@ONLY":
> For most of cmake's variables, simply using them "${CMAKE_SYSTEM}" is
> not enough, you first need the "SET" line:
> SET(CMAKE_SYSTEM "@CMAKE_SYSTEM@")
Joerg, Guilhem.
Maybe it makes things a bit cleared with my explanation, I'll try ..
Apart from cmake main functionality to be used to build software, It can be used just as
normal portable scripting language.
The classic program in cmake scripting language would look like
hello.cmake :
MESSAGE(STATUS "hello, world")
You can run it with
cmake -P hello.cmake
When cmake is in script mode as above, it does not have build-related context, nothing
like
CMAKE_BUILD_DIR , or CMAKE_C_COMPILER_ID . It does not do system introspection, it does
not
have CMakeCache.txt to get variables from, it cannot do ADD_EXECUTABLE or ADD_LIBRARY
(those
commands are not scriptable), and it has zero builtin variables
Often it is desirable to run cmake scripts (cmake -P) as part of make, in places where
people would
otherwise use non-portable bourne shell scripts or non-portable batch files otherwise. it
is often required
to have build-related variables (buld directory etc) in those scripts.
"Configure file during cmake and run during make" is standard trick to accomplish that.
For example.
A script to be configured could look like
hello.cmake.in :
SET(CMAKE_C_COMPILER_ID "@CMAKE_C_COMPILER_ID@")
MESSAGE(STATUS "hello,${CMAKE_C_COMPILER_ID}")
In build it would be used like this :
CMakeLists.txt:
# Configure file during cmake
CONFIGURE_FILE(
${CMAKE_CURRENT_SOURCE_DIR}/hello.cmake.in
${CMAKE_CURRENT_BINARY_DIR}/hello.cmake
@ONLY)
# After configure content of hello.cmake is
# SET(CMAKE_C_COMPILER_ID "MSVC")
# MESSAGE(STATUS "hello,${CMAKE_C_COMPILER_ID}")
# Run configured file during make
ADD_CUSTOM_TARGET (
Foo
COMMAND
${CMAKE_EXECUTABLE} -P ${CMAKE_CURRENT_BINARY_DIR}/hello.cmake
# ^ this is cmake -P hello.cmake
)
Wlad
