Venerable Monks,

I am currently looking for "near miss" examples in Perl.

More specifically I am looking for innocently looking code-examples that are almost but not quite correct and fail spectaculary.

Maybe an example clarifies what I am looking for:

Imagine this piece code: 

use strict;
my @a=(1..100);

for my $i (0..@a-1) {
  print $a[i];
}

[download]
This may be not an idiomatic way to loop but it is semantically ok: @a-1 (in scalar context) is the index of the last element in @a;

Now imagine someone refactors this to use an array-ref instead of an array like this: 

use strict;
my $a=[1..100];

for my $i (0..$a-1) {
  print $a->[i];
}

[download]
This looks similar to the above but is now only "almost" correct - the problem is the expression $a-1. Unfortunately a array-ref in numeric context returns the memory-location (usually a LARGE number) and so this code will probably loop for a very long time (and/or run out of memory eventually). And in case you ask: No, I am not making this up, I have seen it happen...

Anyone with similar examples?

Many thanks!

In reply to catastrophic near misses in Perl by morgon

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