http://qs1969.pair.com?node_id=41693

Sentinel has asked for the wisdom of the Perl Monks concerning the following question:

I'm writing a simple database-type application in which the data needs to be sorted by whichever column the user selects. I'm having trouble figuring out a way to dynamically determine which sort algorithm to use in the main "sort" statement. I'm maintaining the session state, including the variable $sortname, which contains the name of the function containing the appropriate sort function.

If the user wants to sort the data in descending order by the "FirstName" column, $sortname contains "firstname_descending". This would seem useful, since I can say the following:

my @order = sort firstname_descending keys %data;

However, what I WANT to use is:

my @order = sort $sortname keys %data;

That way, if $sortname contains "firstname_descending", this function would still be called:

sub firstname_descending { $data{$b}{'FirstName'} cmp $data{$a}{'FirstName'}; }
Why doesn't that work? How can I use this type of sort architecture?