Filehandles are global, irrespective of the scope in which they are referenced. To say the filehandle closes when the reference count reaches zero is incorrect.

oh well, I can't retract what I know to be true!

No, because that would involve learning something?

use strict;
use warnings;

if (1) {   
   local *FH;
   my $fh = \*FH;
   open $fh, 'ls /usr |';
}

$_ = <FH>;

warn $_;
__END__
ls: write error
readline() on unopened filehandle FH at - line 10.
Use of uninitialized value $_ in warn at - line 12.
Warning: something's wrong at - line 12.
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Or, simpler demonstration:

use strict;
use warnings;

{
    open my $fh, 'ls /usr |';
}
warn "End\n";
__END__
ls: write error
End
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Note how bin/ls complains before the script exits because my $fh is closed when the scope is left, before warn is called.

Yes I know what 'local' does, but this topic has nothing to do with the use of local. Please refrain from confusing people at a lower level than yourself, who need to know, for example, how global variables work!

You could have said, for example, 'Although globals including filehandles do not go out of scope, this behaviour can be avoided using the local keyword' (and then put your example).

Update: in your second example your variable is specifically of lexical scope, but there is an underlying global that gets assigned to $fh which doesn't go out of scope. OK looks like there's a trick going on here. $fh becomes \*{'::$fh'} which is a global that depends on a local. So although the filehandle isn't closed, it does become lexically inaccessible.

One world, one people

Update: in your second example your variable is specifically of lexical scope, but there is an underlying global that gets assigned to $fh which doesn't go out of scope.

No, you are wrong. But you seem doggedly unable to learn on this point so I won't bother trying further to get you to.

- tye        

Filehandles are global, irrespective of the scope in which they are referenced. To say the filehandle closes when the reference count reaches zero is incorrect.

Not quite right, as you know by now, but also not completely wrong. Filehandles are a limited resource, no matter what language you use to write your software. So it is generally a good idea to close filehandles if they are no longer needed.

Modern operating systems with a lot of memory generally allow many file handles, but still you can run out of filehandles:

>perl -Mstrict -w -E 'my @h; for my $i (1..5000) { open $h[$i],"<","/d
+ev/null" or die "$i $!"; }'
1022 Too many open files at -e line 1.
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(Linux 3.10.17 x64)

C:\>perl -Mstrict -w -E "my @h; for my $i (1..5000) { open $h[$i],'<',
+'nul' or die qq[$i $!]; }"
2046 Too many open files at -e line 1.
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(Windows 7 64 Bit)

Alexander

open my $FH, '-|', qw{ ls usr } or die $!;
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After the closing braces, there is nothing left in scope. In spite of that the filehandle FH remains open

... which means that FH is indeed still in scope and that the reference count is therefore non-zero.