[CMake] $<> expressions in include_directories command

[Andreas Pokorny]

Hi,

2011/7/13 Daniel Pfeifer <purplekarrot at gmail.com>:
> 2011/7/13 Andreas Pokorny <andreas.pokorny at gmail.com>
>> [...]
>> add_library(foo ....)
>> target_include_paths(foo include/foo )
>> target_include_targets(foo bar)
>
> target_include_targets would not even be required, target_link_libraries
> could handle that. Whenever a target is linked to a library, it also should
> use the appropriate include directories.

So you mean relying on the status of the assembled "include_directories".
Not sure if you want that behavior, since include_directories  just adds
directories while descending the directory tree.

>
>> [...]
>>
>> The existing include_directories command could "call"
>> target_include_paths(..) internally
>> for all targets defined afterwards..
>
> This works iff there is a 1:1 relationship between targets and directories.
> Boost also has components that provide multiple libraries. And it also has
> (quite a lot) of header-only libraries, these are components that provide no
> library target at all.

I admit that a a no-op or dummy target is missing for header only
libraries. But
I do not get the part with the 1:1 relationship? Could you elaborate...

Nonetheless I believe that your approach allows interesting uses for
other configuration problems.

regards
Andreas Pokorny