[Melbourne-pm] Postfix conditionals and creating lexicals

Alfie John alfiej at opera.com
Thu Jul 12 14:51:41 PDT 2012

On Fri, Jul 13, 2012, at 02:47 AM, Damian Conway wrote:
> The behaviour of a "my...if 0 construct is officially an accident of
> implementation. And is at least partially documented as such in the
> "perlsyn" manpage (under "Statement Modifiers"):
>        NOTE: The behaviour of a "my" statement modified with a statement
>        modifier conditional or loop construct (e.g. "my $x if ...") is
>        **undefined**.  The value of the "my" variable may be "undef", any
>        previously assigned value, or possibly anything else.  Don't rely
>        on
>        it.  Future versions of perl might do something different from the
>        version of perl you try it out on.  Here be dragons.

Ahh. I've never seen any reference to that before. Thanks for pointing
it out.

> However, as "perlsyn" mentions, this relies on undefined side-effect of
> the implementation and is not guaranteed to keep working in future
> versions of Perl. Indeed, in Perl 5.10 and later, if you 'use warnings',
> you get a compile-time warning about the construct.

Maybe it's in a later version? I'm under 5.10.1 and it's not giving me

Dragons begone!


  Alfie John
  alfiej at opera.com

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