Re: Scope problem in closures with an eval statement

I believe the problem is that you use q (single quote) around the print "$str$k, thus the variables were not interpolated.

You should use qq (double quote) instead.

my $print = emphasizePrint();
$print->("Hello World"); ## Prints "Hello World!!"

sub emphasizePrint
{
  my $k = "!!\n";
  return sub {
    my ($str) = @_;
    eval (qq{print "$str$k"});
    print STDERR "Error: $@" if ($@);
  }
}
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Comment on Re: Scope problem in closures with an eval statement Download Code

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Re^2: Scope problem in closures with an eval statement by moritz (Cardinal) on Apr 15, 2008 at 08:55 UTC
That's really a bad idea in the general case, because it won't work if `$k` has a string terminator in it: `sub emphasizePrint { my $k = qq{"!!\n}; return sub { my ($str) = @_; eval (qq{print "$str$k"}); print STDERR "Error: $@" if ($@); } } __END__ Error: Can't find string terminator '"' anywhere before EOF at (eval 1 +) line 2.` [download] In the general case this opens lots of holes, which can be a security risk. I think that citromatik deliberately interpolated the variables at eval time, not prior to evaling the string.	[reply] [d/l] [select]

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Re^2: Scope problem in closures with an eval statement
by moritz (Cardinal) on Apr 15, 2008 at 08:55 UTC

$k

sub emphasizePrint
{
  my $k = qq{"!!\n};
  return sub {
    my ($str) = @_;
    eval (qq{print "$str$k"});
    print STDERR "Error: $@" if ($@);
  }
}
__END__
Error: Can't find string terminator '"' anywhere before EOF at (eval 1
+) line 2.
[download]

In the general case this opens lots of holes, which can be a security risk.

I think that citromatik deliberately interpolated the variables at eval time, not prior to evaling the string.

[reply]
[d/l]
[select]