[cmake-developers] Generator expressisons in target properties

[Stephen Kelly]

Brad King wrote:

> On 11/18/2012 04:12 PM, Stephen Kelly wrote:
>> This will require that the INCLUDE_DIRECTORIES properties not be handled
>> in the regular way, but as a std::vector<IncludeDirectoryEntry> where:
>> 
>> struct IncludeDirectoryEntry
>> {
>>   cmCompiledGeneratorExpression ge;
>>   bool IsCMP0020Entry;
>> };
>> 
>> On the plus-side this means that we'll get proper backtraces from errors
>> in generator expressions for includes.
> 
> That sounds fine to me.  As long as the CMake-language interface
> remains unchanged the underlying implementation of a property
> does not matter.  Just make sure that when someone sets the value
> of the property to a given string and then gets the value they get
> the *identical* original string back.

Yes, that should be possible, but will require some changes to how compiled 
generator expression pointers are memory managed (more auto_ptr).

Interestingly, this would be far far easier if INCLUDE_DIRECTORIES were not 
generator expression capable, so that is a case which shows why it can be a 
bad idea to integrate a finished feature if not all related features are 
also finished. I'll hopefully be able to finish off all of this stuff for 
the next release anyway though.

Thanks,

Steve.