[cmake-developers] Target usage requirements and conventions

[Stephen Kelly]

Alexander Neundorf wrote:

> On Wednesday 02 May 2012, Stephen Kelly wrote:
>> Brad King wrote:
> ...
>> > to mean find-if-necessary.  Then arguments after "Bar" would be
>> > passed to the implied find_package for version and all the other
>> > options.  Either Module mode or Config mode could detect whether
>> > there is enough information to define the Bar package, and then
>> > do so.  See below.
>> > 
>> > This brings up a fundamental question for this design discussion.
>> > Are usage requirements associated with packages, with targets, or
>> > with either/both?
>> 
>> Both, I think. They are associated with targets because properties on
>> targets are what needs to be propagated as required for usage, and
>> because targets will get usage requirements from other targets.
>> 
>> They are associated with packages for compatibility with packages which
>> do not create exported targets, but which do have conventional prefixes
>> on variables.
> 
> Going one step back: why is the package mode then necessary at all ?
> If it is for packages which don't create imported targets, can't the
> VARIABLE_PREFIX mode be used then ?

If a package does not define imported targets and does not use variables 
with a consistent and conventional names, then finding the PACKAGE mode is 
indeed not useful, I think. 

The FIND_PACKAGE mode would find the package of the specified name, if we 
can agree on doing that and the exact syntax for it.

That seems to be the point that there is disagreement on currently though 
indeed.

Thanks,

Steve.