Dan Sugalski wrote:
> At 05:44 PM 9/3/2001 -0400, Ken Fox wrote:
> > Lexicals are fundamentally different from Perl's package (dynamically
> > scoped) variables.
>
> No, actually, they're not.
How can you possibly think that lexical scoping and dynamic scoping
are not fundamentally different?!
> > Even if you could somehow hack package variables
> > to implement lexicals, it would waste space duplicating a symbol table
> > for each instance of a lexical scope.
> The big difference between lexical variables and package variables is that
> lexicals are looked up by stash offset and package variables are looked up
> by name.
Right. So how is a hash table smaller than an array?
> The real question, as I see it, is "Should we look lexicals up by name?"
> And the answer is Yes. Larry's decreed it, and it makes sense. (I'm
> half-tempted to hack up something to let it be done in perl 5--wouldn't
> take much work)
Where is the sense in this? Certainly the compiler will look things
up by name, but the run-time doesn't need to.
> The less real question, "Should pads be hashes or arrays", can be answered
> by "whichever is ultimately cheaper". My bet is we'll probably keep the
> array structure with embedded names, and do a linear search for those rare
> times you're actually looking by name.
That doesn't sound like we're looking up by name at all... It
sounds like the compiler is emiting frame pointer offsets, but
there's a pointer to the symbol table stored in the frame just
in case something wants to see the names.
That's a huge difference over emulating "my" with "temp" like
what was originally proposed!
- Ken
