I had a snippet of my code that went through an array thusly: 
while( shift @array ) { some_operation $_; }

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which wasn't working. I switched to 
foreach( @array ) { some_function $_; }

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and that seemed to work fine. This surprised me. I looked up $_ in the camel book and I found that Perl will assume $_ for "various unary functions" and "various list functions" (in the section on Global Special Variables). This is rather vague. So when is $_ used and when isn't it?

In reply to When does $_ get used? by elbie

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