Re: Inline/gtk2-perl problem solved / patch to Inline::denter.pm

[Ken Williams]

On Thursday, November 14, 2002, at 07:17  AM, Brian Ingerson wrote:

On 13/11/02 16:08 +0100, [EMAIL PROTECTED] wrote:

A problem we had with dynamic loading of Inline modules
has been tracked down to the use of $_ in Inline::denter.
With the attached patch it works OK

Wow. That's crazy. How could $_ affect anything? Would you mind sending a
brief expanation? I'll apply the patch.

$_ is a global variable just like any other. If you clobber it, you may clobber someone else's data.

The reason $_ is usually safe is that you don't generally assign things to it, you let perl do the assigning implicitly (by using a foreach(), map(), grep(), etc.) and in this case it localizes the variable before assignment.

But if you assign explicitly and you don't localize, clobber city.

The following script demonstrates:

#!/usr/bin/perl

top();

sub top {
local $_ = 5;
inner();
print "\$_ is $_\n";
}

sub inner {
$_ = 7;
}

__END__

***************
*** 188,193 ****
--- 189,195 ----
      $o->{done}++, $o->{level} = -1, return unless @{$o->{lines}};
      my ($width, $tabwidth) = @{$o}{qw(width tabwidth)};
      while (1) {
+         local ($_);
  	$_ = $o->{lines}[0];

Incidentally, I'd just write these as

    local $_ = $o->{lines}[0];

 -Ken