Standard for placing any template Find-modules with the original lib? (was: Re: Strange commit to FindKDE4Internal.cmake)

[Alexander Neundorf]

On Friday 17 February 2012, Friedrich W. H. Kossebau wrote:
> Am Freitag, 17. Februar 2012, 19:34:38 schrieb Alexander Neundorf:
> > On Friday 17 February 2012, Friedrich W. H. Kossebau wrote:
> > > Am Freitag, 17. Februar 2012, 17:33:34 schrieb Alexander Neundorf:
> > > > A library must never install the Find-module for itself.
> > > > 
> > > > This defeats the purpose. This is like putting the remote control
> > > > right next to the TV, or the treasure map right into the treasure
> > > > chest. You don't know where the plan is, but once you found the
> > > > plan, you already found what you are interested in and don't need
> > > > the plan anymore.
> > > 
> > > That reminds me of something I wanted to ask for a while:
> > > 
> > > A few libraries provide in their sources a template for the Find-module
> > > for
> > > itselves, as a nice starting point for devs using the lib and needing
> > > that Find-module.
> > > 
> > > But IIRC those libs had the template file in the same "cmake/modules"
> > > subdir where also the normal Find-modules which are actually used by
> > > the lib's buildsystem are located. A little bit confusing, at least
> > > for me the template file would be ideally in a separate file and even
> > > have a special name, like "Find*.cmake.template" or similar, to help
> > > discoverability.
> > > 
> > > Do you have a proposal or know a pattern-to-follow how to name and
> > > where to
> > > place such Find-module templates? Would be nice if there could be some
> > > standard.
> > > 
> > > E.g. for my RIFF-parser lib libkoralle I would like to ship a template
> > > Find- module, but also want any user of the lib discover what I
> > > provided for them, so my work is not uselessly duplicated. Placing
> > > that in extra-cmake-modules would help only KDE-centric devs, no?
> > 
> > No, extra-cmake-modules will have no KDE dependencies at all, it is
> > explicitely meant for everybody (which also includes KDE).
> > 
> > There will be the first release this spring or early summer, at the
> > latest at the same time of the first KDE frameworks
> > alpha/beta/preview/whatever release.
> > 
> > So, if you want to distribute a Find-module, without getting it into
> > cmake, but also without any additional dependencies, extra-cmake-modules
> > will be the place to put it.
> 
> Hm... then I see an issue with extra-cmake-modules:
> any lib released since the latest extra-cmake-modules will not be
> supported, if there is a BIC change in it. 

There shouldn't be BIC changes that often ?

> Will suck especially with also
> adding distribution releases into the game, which might pick up the latest
> lib version, but an older extra-cmake-modules which has not yet support
> for that lib version.

There will be frequent releases, at least every three months, maybe monthly.
They should pick up the most recent one.
And it will be dead easy to install multiple versions at the same time, in 
your home.

> So any dev wanting to make use of that lib cannot rely on
> extra-cmake-modules and has to do things himself.

I don't think so.
He can say
find_package(extra-cmake-modules 1.5.23 REQUIRED)
and then everybody who builds it must have at least this version installed.
If it's not installed, simply download the release from <somewhere> and unpack 
it wherever you want, and point CMAKE_PREFIX_PATH to it.

> Which somehow renders
> extra-cmake-modules a little bit useless for me (as usually as dev you
> want the latest-and-coolest version of some lib).

Well, if this is what you want as developer then you can also require the 
latest-and-greatest extra-cmake-modules ;-)

> Or will extra-cmake-modules be some kind of online-repo of cmake modules
> with a rolling release, so if you need some Find-module you always grep
> what is there, hoping someone has already done support for any latest
> version? Where each module is independently updated, without a real
> version, like Wikipedia pages?

This is currently not planned, but you are free to get involved and help make 
it so :-)

Alex