[Insight-developers] USE_EXTERNAL cmake flag

[Alexandre GOUAILLARD]

gaetan,

I just saw two new variables in ITK cmake configuration:
ZLIB_USE_EXTERNAL and SZIP_USE_EXTERNAL.

As we are using external for GCC_XML and we are planning to do so for
swig as well, would it be interesting for us to do the same thing?

A global question now, there are now three ways of including external libs:
- getting the included ThirdParty Module when available
- using a system install
- using the external_project feature of cmake.


what is the rationale when choosing between one or the other?
Should we support all of them ?
I remember that the rules about having ThirdParty modules are very
clear (Licence, size, ...)
Now the SYSTEM part is almost clear to me :-)
But what about choosing between SYSTEM and external?

alex.