Suggested patch for FindOpenGL.cmake

[Brad King]

Paulo Jorge Guedes wrote:
>> -----Original Message-----
>> From: Paulo Jorge Guedes [mailto:Paulo.Guedes at artelecom.pt]
>> Sent: terça-feira, 20 de Junho de 2006 19:16
>> To: kde-buildsystem at kde.org
>> Subject: RE: Suggested patch for FindOpenGL.cmake
>>
>>> -----Original Message-----
>>> From: David Faure [mailto:faure at kde.org]
>>> Sent: terça-feira, 20 de Junho de 2006 9:27
>>> To: kde-buildsystem at kde.org
>>> Subject: Re: Suggested patch for FindOpenGL.cmake
>>>
>>> On Monday 19 June 2006 22:12, Alexander Neundorf wrote:
>>>> On Monday 19 June 2006 00:14, David Faure wrote:
>>>>> Why look for X11 again, if we did so already before?
>>>>> [e.g. due to FindQt4.cmake]
>>>>> This should save a bit of time in reconfiguring, since FindX11 has a
>>> rather
>>>>> large set of checks (it's even larger in kde's version of it, due to
>>>>> additional libs), and since FindX11 doesn't have a fast path when
>>> things
>>>>> are in the cache already (it rechecks every time).
>>>> Does this have a measurable effect ?
>>> It has at least the effect that I dont see "Xpm not found" 4 times in
>>> kdebase :)
>>>
>>>> Detecting the stuff (the find_xxx() calls) automatically uses the
>> cache.
>>> Take a look at our FindX11.cmake - there is a lot going on there, not
>> just
>>> find_xxx.
>> I think this is screaming to be automated. It would be great if cmake
>> could offer some mechanism to do this checking automatically.
>> Perhaps some list where we could add the variables that would define if
>> the checking for a particular module is completed, e.g.:
>>
>> FindX11.cmake:
>>
>> set_required_vars(X11_FOUND)
>>
>> Then, cmake would automatically check the required vars at the beginning
>> of each module and would return if they were satisfied, and the user could
>> happily try to find the packages without worrying about performance or
>> output.
>>
>> What do you think?
> 
> Maybe this could be even easier. 
> It seems to be a standard to define a variable named "FOOBAR_FOUND" for a "FindFoobar.cmake" module. This means that "FOOBAR_FOUND" could be automatically added to the required variable list so that, in the majority of the cases, the user shouldn't have to write any code at all (if he follows this standard).

FindOpenGL.cmake could use the line

   FIND_PACKAGE(X11)

to look for the X11 package.  We could add a short-cut in FIND_PACKAGE 
to skip doing anything if X11_FOUND is already set to true.  Does this 
do what you want?

-Brad