The exists function is defined to return truth if the specified element exists, false if it does not.

In a previous discussion, we determined that a statement that uses an element if that element exists is not optimized to do the lookup only once, and in Perl6 "the situation is even worse".

Well, testing to see if an element exists before using it is a common use of exists. So, if the "true" value it returned were a reference to the element, then one could refer to it without looking it up again.

Finding an occurance in the file I'm currently working on, 

return $export_def->{'..client_default_version'}{$client}  if exists $
+export_def->{'..client_default_version'}{$client};

[download]
would become something like 
return $$e if my $e= exists $export_def->{'..client_default_version'}{
+$client};

[download]
—John

In reply to optimization - exists should return a reference by John M. Dlugosz

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