Precedence (spot the bug)

I just spent longer than I care to admit on this one...

opendir(DIR,'/') || die "$!";
my @files=readdir(DIR)  || die "$!";
closedir(DIR) || die "$!";
print join "\n", @files;
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select this for answer:

|| has a higher precedence than =

(my @files=readdir(DIR)) || die “$!”;

.....works just fine

email: mandog

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Re: Precedence (spot the bug)
by Chmrr (Vicar) on Oct 22, 2001 at 05:07 UTC

Ayup. Note that or is identical to || but with a lower precence; thus, it's rather practical for things like this. Generally, || is used mainly to establish default values, because of its high predence.

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^+*`^ ve^#$&V"+@( NO CARRIER'

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Re: Precedence (spot the bug)
by Arguile (Hermit) on Oct 22, 2001 at 05:16 UTC

You might consider using the lower precedence "or" especially for error checking. The double pipe version is more useful for when you want to do short-circuit evaluation in conditional expressions.

opendir DIR, '/'
  or die "Failure opening dir /: $!";
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Stylistically I find this much easier to read and you don't have to worry about precedence as 'or' and 'xor' are as low as you can get on the chart ;).

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Re: Precedence (spot the bug)
by kschwab (Vicar) on Oct 22, 2001 at 05:09 UTC

my @files=readdir(DIR) or die “$!”;

.....works just fine too.

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