open FOO || die "Argh: $!\n";
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open (FOO) || die "Argh: $!\n";
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And in the case we are discussing here, || is very much wrong. Consider the first example of || die in the posted code:

mkdir "$dir", 0777 || die "Could not mkdir \"$dir\": $!\n";
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Here is a demonstration of why this is wrong:

my $dir= "source"; # A directory that I know exists.
warn "Using or...\n";
mkdir "$dir", 0777 or die "Could not mkdir \"$dir\": $!\n";
warn "Using ||...\n";
mkdir "$dir", 0777 || die "Could not mkdir \"$dir\": $!\n";
warn "Done.\n";
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This produces the following output:

E:\etm\Work>perl -w mkdir.pl
Using or...
Could not mkdir "source": File exists
Using ||...
Done.
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Note that -w was silent as well, so I'm not sure when it will warn me of a precedence problem (I'm using Perl 5.6.0).

        - tye (but my friends call me "Tye")

i'm using 5.005_03, and this is what happens when i try to use || in a naughty way:


#!/usr/bin/perl
$FOO="/etc/passwd";
open FOO || die "Argh: $!\n";
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results in:


nooky:~$ ./foo.pl
Precedence problem: open FOO should be open(FOO) at ./foo.pl line 3.
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Running with -w like a good boy produces even more useful output:


nooky:~$ ./foo.pl
Precedence problem: open FOO should be open(FOO) at ./foo.pl line 3.
Probable precedence problem on logical or at ./foo.pl line 3.
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I have not played with 5.6 yet, but I'd be a little upset if this feature was removed....

BlueLines

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Ah, that only works for open. Thanks for clearing that up.

        - tye (but my friends call me "Tye")