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Re: Perl OO: Need a concise way of representing operations on an object

by rjt (Deacon)
on Nov 04, 2012 at 10:25 UTC ( #1002182=note: print w/replies, xml ) Need Help??


in reply to Perl OO: Need a concise way of representing operations on an object

The trick here is to return a closure from a generator function. Below is a complete working example. However the salient bit is returning refs to $cont and $foo from the generator function, and dereferencing them in the caller to initialize or change them.

package Foobar; sub _setup_xforms { my ($cont, $foo); return (\$cont, \$foo, { xform1 => sub { printf("Level %d,foo=%s\n", $cont, $foo); +}, }); }; sub transform { my ($self, $cont) = @_; my ($cont_ref, $foo_ref, $xforms) = _setup_xforms(); $$cont_ref //= $cont; # //= to convince you it's not still set for my $xform (values %$xforms) { $$foo_ref //= 0; # //= as above $xform->(); $$foo_ref++; $self->transform($cont + 1) if ($cont < 5); print "Level $cont done, foo=$$foo_ref\n"; } } sub new { bless({},'Foobar') } my $foo = new Foobar( id => 1 ); $foo->transform(0);

This produces the following output:

Level 0,foo=0 Level 1,foo=0 Level 2,foo=0 Level 3,foo=0 Level 4,foo=0 Level 5,foo=0 Level 5 done, foo=1 Level 4 done, foo=1 Level 3 done, foo=1 Level 2 done, foo=1 Level 1 done, foo=1 Level 0 done, foo=1

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Re^2: Perl OO: Need a concise way of representing operations on an object
by wanna_code_perl (Pilgrim) on Nov 05, 2012 at 00:45 UTC

    This is exactly the solution I was looking for. It looks like it'll be easy to extend.

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