in reply to Re: Re: Closures and sort
in thread Closures and sort
The obvious answer would be to add a method reset_count() in the block, but you would have to explicitly call it before sorting, which is prone to errors.
Another way is to put together a state and a behaviour, building an object.
But if you want to go on in a functional way, you may want to build a composition of a behaviour and a state, i.e. a closure. Here a short demonstration:In order to learn more about this subject (very interesting, in my opinion) you could refer to the following online resources:use strict; my @list1 = qw/ box cow dog apple ant/; my @list2 = qw/ ant apple box cow dog/; sub make_a_profilable_sorter { my $criterion = shift; return sub { my $counter = 0; my @list = @_; @list = sort { $counter++; $criterion->( $a, $b ) } @list; return ( $counter, @list ); } } my $sorter1 = make_a_profilable_sorter( sub{ $_[0] cmp $_[1] } ); my $sorter2 = make_a_profilable_sorter( sub{ $_[0] cmp $_[1] } ); my ($count, @res) = $sorter1->( @list1 ); print "I sorted /@list1/ in $count steps producing /@res/\n"; my ($count, @res) = $sorter2->( @list2 ); print "I sorted /@list2/ in $count steps producing /@res/\n";
- Frames as repository of local state in Structure and Interpretation of Computer Programs
- On Lisp by Paul Graham. Start at page 30 (in the free pdf file)
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