Re^2: Avoiding vivification with array slice

[jbert]

in reply to Re: Avoiding vivification with array slice
in thread Avoiding vivification with array slice

Cool. Accessing $a[$i] isn't enough to vivify (otherwise your defined test would do it).

So we don't actually need the defined test in your map and can get away with:

# This *doesn't* vivify $a[3,4,5]
@b = map { $a[$_] } (0..5);

Thanks.

[ikegami]

The point of the defined wasn't to prevent autovivification, but to implement the grep you had in your original code. The following two snippets are equivalent.

@b = map { defined($a[$_]) ? ($a[$_]) : () } 0..5;

@b = grep { defined } map { $a[$_] } 0..5;

What you suggested (@b = map { $a[$_] } 0..5;) is *not* equivalent.