Re^2: Logical/defined or as lvalue

[jo37]

When would it be useful?

Consider items from @list to be counted, with one "given" set and a "rest". A pre-initialized hash %h1 holds the "given" set and an empty hash %h2 counts the rest. Then we could:

${\($h1{$_} // ($h2{$_} //= 0))}++ for @list;

[ikegami]

If you're going to count them all, I don't see the point of having the counts split across two hashes. If there's an important distinction between the two sets of strings, you would need those lists, and you could access the counts of either lists.

[LanX]

If I wanted to do this, I'd count only in one hash and use a hash-slice to extract the "given" ones.

Less code and more flexible.

Update

Alternatively a HoH where the first key decides what is given or rest.