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Postings from February 2004
Joe Gottman asked:
> How do you decide whether a key-extractor block returns number? Do you
> look at the signature, or do you simply evaluate the result of the
> key-extractor for each element in the unsorted list? For example, what is
> the result of the following code?
>
> sort {$_.key} (1=> 'a', 10 => 'b', 2 =>'c');
>
> There is nothing in the signature of the key-extractor to suggest that
> all the keys are numbers, but as it turns out they all are. Will the sort
> end up being numerical or alphabetic?
Whilst I'd very much like it to analyse the keys, detect that they're all
numbers, and use C<< <=> >>, I suspect that if C<sort> can't determine that
the return type of the key extractor is numeric, it will have to default to
C<cmp>. Otherwise a case like this:
sort {$_.key} (1=> 'a', 10 => 'b', '2' =>'c');
becomes a little too subtle.
And, after all, it isn't that much extra work to force the issue:
sort {+$_.key} (1=> 'a', 10 => 'b', 2 =>'c');
vs:
sort {~$_.key} (1=> 'a', 10 => 'b', 2 =>'c');
Damian
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