$return in wildcarded void functions

[Mike Mason]

Frank Ch. Eigler wrote:
> Hi -
> 
> On Tue, Mar 06, 2007 at 02:05:39PM -0800, Mike Mason wrote:
>> [...]
>>> So:
>>>   $?var==0 implies $!var==0
>>>   $?var==0 implies $var would have caused compile-time error
>>>   $?var==1 implies $!var equals what $var would have
>> I like this approach.  Could it also work for variables defined locally in 
>> probes (e.g. ?var and !var, no $)?  What about global variables?
> 
> I can't think of any reason to apply it to normal script variables.
> The point here is to adapt to vagaries of the probed software, not the
> probe script itself.

I should have said "locally in *tapset* probes".  Tapsets themselves may change just like the probed software, though we have more control over that.  Supporting this approach for tapset variables would help us to write user scripts that work with multiple versions of systemtap, even if variables are missing in some versions.

Mike