Hendrik Sattler wrote:
Quoting Bill Hoffman <[EMAIL PROTECTED]>:
OK, I get it now... So, the FIND_* stuff will set a value if it is
NOTFOUND. However, the set command will not. I am thinking it should.
I am not sure what that will break, but it would be consistent with
FIND_*.
This should not be a problem if you start from a clean build tree for
FindQt4.cmake, as QT_INCLUDE_DIR will never get put in the cache as
NOTFOUND by the current FindQt4.cmake. So, I think this is something
we can fix in CMake 2.6. Feel free to create a feature request, "set
CACHE should set NOTFOUND variables".
Let's say a library is optional. A current script cannot see the
difference anymore between "library not found on earlier run" and "I did
not search for it, yet". SET is well-documented about CACHE and FORCE
behaviour. Don't break that as you can always use
if (NOT DEFINED VAR)
set (VAR "foo" CACHE ...... FORCE)
But:
find_library(FOO_VAR foo)
This will set FOO_VAR (in the cache) if it is not set, or if the value
has -NOTFOUND in it.
However,
set(FOO_VAR somevalue CACHE STRING "")
Will only set FOO_VAR if it has no value at all. Seems a bit
inconsistent.
-Bill
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