[Phoenix-pm] Eval Namespace Question

[Bill Nash]

If you're excited about perl forwarding that namespace into your eval, 
just remember that's a double edged sword. When you're to a point where 
you're thinking about efficiency, or perl starts to core dump with 
frightening regularity, revisit your use of eval.

- billn

On Mon, 7 Aug 2006, Douglas E. Miles wrote:

> Hey all!
>
> I'm having fun hacking Perl for a change, and I just realized I'd been
> using a feature that I don't completely understand.  man perlfunc says
> this about eval:
>
> In the first form, the return value of EXPR is parsed and exe-
> cuted as if it were a little Perl program.  The value of the
> expression (which is itself determined within scalar context)
> is first parsed, and if there weren't any errors, executed in
> the lexical context of the current Perl program, so that any
> variable settings or subroutine and format definitions remain
> afterwards.
>
> This means that in my code below, that $bar is in scope within the
> eval.  What blows me away is that $foo::foo is also in scope because of
> the "package foo" statement in $eval_string.  Does anyone know how perl
> accesses both namespaces simultaneously without specifying the namespace
> in each variable name.  Feel free to laugh at me if I'm missing
> something basic. :)  The cool thing is that this behavior is exactly
> what I need.  I'd just like to understand how it works (and hope that it
> isn't a misfeature that might be removed in the future).  Thanks!
>
>
> #!/usr/bin/perl
>
> package foo;
>
> $foo = "FOO!";
>
> package bar;
>
> my $bar = "BAR!";
>
> my $perl_code = 'print "$bar $foo\n"';
> print "$perl_code\n";
>
> my $eval_string = "package foo;\n$perl_code";
> eval $eval_string;
>
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