[cmake-developers] Adding argument "OPTIONAL" to find_package() and add_subdirectory

[Alexander Neundorf]

On Wednesday, June 08, 2011 08:45:56 PM Eric Noulard wrote:
> 2011/6/8 Alexander Neundorf <neundorf at kde.org>:
> > On Tuesday, June 07, 2011 02:34:06 PM Eric Noulard wrote:
> >> 2011/6/7 Alexander Neundorf <neundorf at kde.org>:
> >> > On Monday, June 06, 2011 03:26:03 PM Brad King wrote:
> >> >> On 06/04/2011 06:30 AM, Alexander Neundorf wrote:
> >> [...]
> >> 
> >> >> > What do you think about adding the keyword OPTIONAL to
> >> >> > add_subdirectory ?
> >> >> > 
> >> >> > Both have been proven useful, the one for find_package() especially
> >> >> > for packagers.
> >> >> 
> >> >> Ditto previous response.  These commands are primitives.  We should
> >> >> not extend them with features unrelated to their basic purpose.
> >> > 
> >> > While this is correct, it also keeps cmake a bit low-level.
> >> > For this reason, we created such macros in KDE.
> >> > Now our developers write stuff outside KDE, so either they can't use
> >> > it, or they create copies of these files.
> >> > This may be ok, but having 50 or 100 versions of these files and
> >> > macros around in the net, some probably differing slightly, is also
> >> > not a nice situation.
> >> 
> >> Then it is possible to create a new CMake module,
> >> 
> >> say
> >> 
> >>  UseEnhancedConfigure.cmake
> >> 
> >> which could be included in CMake as a contributed module maintained by
> >> KDE dev. This new module would define something like:
> >> 
> >> optional_find_package().
> >> optional_add_subdirectory()
> >> 
> >> this would make the feature available upstream, thus available outside
> >> KDE and does not add extra feature to builtin configure.
> > 
> > I can't think of any reason why somebody would want to use
> > find_package(...without REQUIRED) instead of optional_find_package().
> > 
> > Can somebody else see a reason ?
> 
> Our e-mails crossed each-other.
> 
> Yes you are right default behavior of making find_package(...without
> REQUIRED) This is a different story for add_subdirectory.

Yes, for me adding this to find_package() is the more important and more 
general useful one.

Alex