Brad King wrote:
Philip Lowman wrote:
On Wed, Aug 20, 2008 at 10:54 AM, Brad King <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
The "set" command already supports unsetting:
set(FOO xyz)
set(FOO) # unsets
if(DEFINED FOO)
message("This message does not appear.")
endif(DEFINED FOO)
I think it should just be fixed for CACHE and ENV variables.
I knew that set() supported unsetting local variables but wasn't sure it
would be safe to extend it to CACHE and ENV variables as a bugfix.
Regardless of whether this is appropriate to do or not adding an unset()
command also seemed to make the language simpler to understand because:
set(FOO)
as someone else pointed out, is somewhat confusing. Without referencing
the documentation many programmers might think this defines a variable
called FOO and sets it to empty but what it really is doing is
*undefining* the variable FOO entirely if it exists.
Okay, I agree. It will be easier and more readable to add the unset
command than to extend the "set" command to "unset" things :)
However, this:
unset(MY_CACHE_VARIABLE)
should not remove the cache entry. It should only unset the CMake
variable. In order to remove the cache entry, we should require
unset(MY_CACHE_VARIABLE CACHE)
Otherwise there is no way to remove the variable without removing the
cache entry.
Makes sense.
And while you are it.. I currently use: set(var) to read the value
back from the cache (very usefull somtimes), but this is undocumented
and extremely none-obvous, so, can we have a "fetch(var)" as well?
Should I formally suggest that via a bug report?
TIA
Fernando Cacciola
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