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From: bjaspan@athena.mit.edu (Barr3y Jaspan)
Newsgroups: comp.lang.perl
Subject: default associative array sort function
Message-ID: <1991May14.045945.11077@uvaarpa.Virginia.EDU>
Date: 14 May 91 04:59:45 GMT
Sender: mmdf@uvaarpa.Virginia.EDU (Uvaarpa Mail System)
Reply-To: bjaspan@athena.mit.edu
Organization: The Internet
Lines: 27


I frequently have associative arrays that map strings to integers;
say, $users{$username} = # of pages printed on a printer.  Sorting
such an associative array requires writing a special-purpose function

sub sort_users {
	$users{$a} <=> $users{$b};
}

and then call sort sort_users %users.  This works fine but is a pain;
I have to create a separate sort function for each assoc array, when
really I shouldn't have to create one at all (this is a frequent
enough operation, I think...)

How about adding a default sort-assoc-array-{numerically,
lexigraphically} function, so that (sort MAGIC_FUNC %users) would
work?  Even better would be if the sort function recognized that it
was dealing with an assoc array, figured out whether the values were
numbers or strings, and choose the right value, so that (sort %users)
would do the right thing.  ("Figuring out whether the values are
numbers or strings" is, of course, not necessarily trivial.  You could
implement some specific heuristic and document it, given the
programmer the choice of overriding the heuristic when necessary.)

print((sort (' another', ' Just', ' perl ', 'hacker,')), "\n");

Barr3y