The reason map (and for/foreach and grep) make an alias instead of a copy is speed. A lot code, probably a majority of the code, doesn't modify $_ inside a map or grep; slightly less code will not modify $_ (or the loop variable) inside a for/foreach.

If don't plan to modify $_, having an alias instead of a copy means the data doesn't have to be copied, saving memory and speed. This benefits everyone; the only case where extra code is needed is where one modifies $_ without the intention to modify the original array. That code has to do the copy explicitely.

IMO, the right choice has been made.

In reply to Re^2: Changing array by changing $_? by JavaFan
in thread Changing array by changing $_? by johnvandam

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