[CMake] Triggering individual steps of externalproject_add add cmake time

[Jan Wurster]

 Hi David,

 thanks for your help and suggestions! 

> From: David Cole [mailto:david.cole at kitware.com] 
> Sent: Donnerstag, 28. April 2011 19:57
> Subject: Re: [CMake] Triggering individual steps of
externalproject_add add cmake time
>
> I would strongly encourage you to allow the download to occur at build
time using 
> ExternalProject_Add. There's no need to make the configure step of
CMake wait for a 
> download.

 The point only was to solve the .. ahem .. hen and egg problem I'm
encountering at the first ever configure run. Configure of the project
itself needs a certain structure of 3rd party stuff to be available -
else it fails for this system, thus never creating a valid build
structure in the first place.

 I definitely agree the configure step should be kept as minimal in its
timewise requirements as possible, so once the general structure is
present, subsequent calls to cmake would never have retriggered the
download at configure time ;) 

 Your suggestion actually is what I've implemented since and it works
fine. Initially, the download occurs, after that the build process will
keep data up to date. Thanks and best regards,
Jan