develooper Front page | perl.perl6.language | Postings from June 2006

Re: lexical lookup and OUTER::

Thread Next
Audrey Tang
June 24, 2006 16:53
Re: lexical lookup and OUTER::
Message ID:

在 2006/6/24 上午 8:41 時,Patrick R. Michaud 寫到:
>> because later in the scope $x may be declared, so it's safer to just
>> put OUTER right there.
> I don't think $x can be declared later in the scope.  According to  
> S04,
>     If you've referred to $x prior to the first declaration,
>     and the compiler tentatively bound it to $OUTER::x,
>     then it's an error to declare it, and the compiler is
>     allowed to complain at that point.

Hmm, looks like it's been changed this April.  In that case, indeed  
the emitter can safely remove the implicit OUTER calls. Pugs's Parrot  
backend has been updated accordingly.  Thanks!

(...and Cc'ing p6l for the part below)

However, the spec wording is ambiguous:

     $x = 1 if my $x;

The compiler is "allowed" to complain, but does that means it's also  
okay to not die fatally, and recover by pretending as if the user has  
said this?

     # Current Pugs behaviour
     $OUTER::x = 1 if my $x;

If it's required to complain, then the parser need to remember all  
such uses and check it against declaration later, and it'd be better  
to say that in the spec instead.

Thread Next Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at | Group listing | About