access pointer and global variables

[Stone, Joshua I]

David Smith wrote:
> I agree with you that this might be implementable, but is it what you 
> would really want?  In a return probe would you want the original value 
> of $prev->pid or the current value (assuming the function changed the 
> data pointed to by $prev)?
> 
> I'd guess that most times you'd want the current value.

That's a hard question to answer, because it can easily go either way. 
For strace-like scripts, you generally want to say "this function with 
these arguments produced this return value" -- so you want the original 
values.  But there are certainly times when you want to see how the 
arguments were updated.

For a lot of cases, I think the arguments aren't modified, so it 
wouldn't matter when you read them.

I think we can either find a way to do both, for the best flexibility, 
or else pick the one that's the most sane (implementable? matches most 
users' expectation?) and document how it works.


Josh