[cmake-developers] CMake usage requirements in KDE Frameworks

[Brad King]

On 03/19/2013 04:02 PM, Alexander Neundorf wrote:
> On Tuesday 19 March 2013, Stephen Kelly wrote:
>> I don't mind renaming it, but it's a topic for the cmake list.
> 
> So, I think the variable name CMAKE_BUILD_INTERFACE_INCLUDES is to general.
> Since it is similar to the effect of CMAKE_INCLUDE_CURRENT_DIR, I suggest 
> renaming it e.g. to CMAKE_INCLUDE_CURRENT_DIR_IN_INTERFACE.

The proposed name is much better.  The old name was never in a final
release so it is easy to rename now:

 http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=fc43477d

>> applies to both the BUILD and INSTALL include interfaces. To limit it to
>> one or the other, you have to specify it:
>>
>>  target_include_directories(foo INTERFACE
>>    "$<BUILD_INTERFACE:/foo/interface/only>"
>>  )
> 
> Why was this generator expression approach chosen over simply adding suitable 
> keywords, as it is done for all other cmake commands ?
> 
> target_include_directories(foo INTERFACE_BUILD ${CMAKE_CURRENT_SOURCE_DIR} 
>                                                ${CMAKE_CURRENT_SOURCE_DIR}/whatever/
>                                                ${CMAKE_CURRENT_BINARY_DIR}
>                                INTERFACE_INSTALL ${INCLUDE_INSTALL_DIR} ) 

The keywords won't interact well with PUBLIC/PRIVATE/INTERFACE keywords.
Also the arguments are likely to be built up in lists:

  target_include_directories(foo PUBLIC
     ${foo_INCLUDE_DIRS} ${other_INCLUDE_DIRS}
    )

that may or may not contain multiple entries and multiple uses of each
$<BUILD_INTERFACE:...> and $<INSTALL_INTERFACE:...> expression.
The generator expressions bind tightly.

-Brad