[CMake] Howto unset cache variable without UNSET()

[Tyler Roscoe]

Marcel,

Maybe I missed it earlier ITT, but I don't understand why you can't just
use if(FOO) instead?

tyler

On Thu, Jul 01, 2010 at 11:53:33AM +0200, Marcel Loose wrote:
> 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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> 
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