I'm no internals wizard, but I think you're right on the mark.

But more importantly, this is the correct behavior. The purpose of the warning is (presumably) a second line of defense behind strict, for detecting a mispelled variable names. It's purpose probably isn't to warn you that you didn't use it enough, but rather, that not using an undeclared variable means you may (probably do) have a typo.

In the case of a my declared variable, You'll actually still get the warning if you typo it OTHER THAN in the my call. But if you're using my... shouldn't you also be using strict? I am curious as to the thought process that would lead to using only one of the two.

Examples: 

perl -we 'my $foo; $fooo = 42'
Name "main::fooo" used only once: possible typo at -e line 1.

[download]
Typo was still detected. 
perl -we 'my $fooo; $foo = 42'
Name "main::foo" used only once: possible typo at -e line 1.

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Typo still detected. 
perl -we 'my $fooo;'

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No warning. If it is a typo is questionable. It is like a program with no output; if it DOES anything is a matter for some philosophers. But it doesn't matter. Declaring an extra my var doesn't hurt anything. And if you group all your my calls together like my( $foo, $bar, $baz, ) then it doesn't even waste much time. On many systems, I doubt the difference would be measurable.

And so even in all the examples given prior, the correct behavior of identifying harmful typos is always taken.

Personally, I think it's terrible to write code without strict, when it's code that is important enough, or will last long enough, or is intricate enough, that warnings are needed or used. I would only recommend forgoing use strict on once-off one-liners (ie, system administration and playing around).


--
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In reply to Re^2: How do I find out which variables I'm not using? by Aighearach
in thread How do I find out which variables I'm not using? by amyoungil

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