[CMake] How to avoid continuous download while using ExternalProjects

[Luigi Calori]

Hi Philip

Philip Lowman wrote:
> On Wed, Feb 10, 2010 at 11:37 AM, David Cole <david.cole at kitware.com> wrote:
>   
>> If anybody has other ideas to share downloads between "Release" and "Debug"
>> configurations, or other ways to avoid "unnecessary" downloads better, or
>> other ideas for any ExternalProject improvement, I'm all ears. :-)
>>     
>
> Caching for source tarballs would be a nice feature so that when you
> clean the project you don't have to redownload them.  I pulled this
> off with stamp files in CMakePorts I think with some suggestions from
> you.  The problem of course is if you really want to remove the
> downloads you need yet another target.
>   
I'm trying to experiment with this...
What I do not really catch is why the file dependencies are set up using 
stamp files instead of real downloaded files.
Probably more insight on how CMake is treating dependendencies at file 
and target level seem really needed.
> Also, for any that are interested, beta releases of zlib now have a
> CMakeLists.txt in them.  It could use testing on Mac OSX and other
> unix systems.
> http://zlib.net/current/beta/
>   
Did you tried that? I' did but seem to have a strange error on linking 
their examples:
I got
zlib.lib(gzlib.obj) : error LNK2019: unresolved external symbol 
_snprintf referenced in function _gzdopen

that seem to get away by adding
#  define snprintf _snprintf
to gzguts.h
Anyone has ever tested it under MSVC? It would be nice to have helpers 
to build patches, as in CMakePorts...
>
>