[CMake] Howto unset cache variable without UNSET()

[Marcel Loose]

Hi Fraser,

It doesn't. Well, partly it does, but unfortunately setting FOO to an
empty string doesn't make it undefined; i.e. if(DEFINED FOO) will be
TRUE. I've decided to use 'if("${FOO}" MATCHES "^$")' instead.

Best regards,
Marcel Loose.

On Wed, 2010-06-30 at 10:57 +0100, Fraser Hutchison wrote:
> I think 'set(FOO "" CACHE INTERNAL "Foo")' should do the trick.
> 
> All the best,
> 
> Fraser.
> 
> 
> 
> On 30/06/2010 9:38 AM, Marcel Loose wrote:
> > Hi all,
> >
> > Is there a way to unset a cache variable, i.e. make it undefined,
> > *without* using unset().
> >
> > My reason for asking is that my CMake scripts need to be backward
> > compatible with every 2.6 version. Unfortunately, unset() was added
in a
> > patch release (2.6.3 if I recall correctly), so I cannot use it.
> >
> > The problem is that, though 'set(FOO)' will make FOO undefined, this
> > doesn't seem to work for 'set(FOO CACHE INTERNAL "Foo")'.
> >
> > Any ideas how to accomplish this?
> >
> > Best regards,
> > Marcel Loose.
> >
> >
> >
> >
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