in reply to Re: How to morph a plain module to OO (use a compatibility layer)
in thread How to morph a plain module to OO
A function-based API can be (almost) automatically generated from methods -- all you need is a customized import sub. A default object is created during import and each package using the module has a private default object. This approach usually works a bit better than Flexx's because (1) it avoids creating lots of temporary objects, and (2) there's a long-lived object around to hold module state, so all the state-setting methods still work.
I wouldn't recommend the CGI.pm module for studying this technique. CGI.pm is difficult to understand because of its long and glorious history. Take a look at my code below, read the docs on packages and symbolic references, look at Exporter.pm and then you're ready to crack open CGI.pm.
## MyClass.pm package MyClass; use strict; my @export = qw(verbose isFile); sub new { my ($class, %args) = @_; my $self = {verbose => $args{verbose} || 0}; return bless $self, $class; } sub verbose { my $self = shift; $self->{verbose} = shift if @_; return $self->{verbose}; } sub isFile { my ($self, $file) = @_; my $found = -f $file; if ($self->verbose) { print STDERR "$file ", ($found ? 'found' : 'not found'), "\n"; } return $found; } sub import { my $module = shift; my $mode = shift || ':methods'; if ($mode eq ':functions') { no strict 'refs'; my ($package) = caller(); my $object = MyClass->new(@_); foreach my $name (@export) { my $sub = $MyClass::{$name}; *{$package.'::'.$name} = sub { &{$sub}($object, @_) }; } } } 1; ## test.pl package verbose_main; use strict; use MyClass (':functions', verbose => 1); sub test { if (isFile('MyClass.pm')) { print "ok\n"; } if (verbose()) { print "verbose mode on\n"; } } package quiet_main; use strict; use MyClass (':functions'); sub test { if (isFile('MyClass.pm')) { print "ok\n"; } verbose(1); if (isFile('NotFound')) { print "ok\n"; } } package oo_main; use strict; use MyClass; my $env = MyClass->new(verbose => 1); sub test { if ($env->isFile('MyClass.pm')) { print "ok\n"; } } package main; use strict; verbose_main::test(); quiet_main::test(); oo_main::test();
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Re: Custom import for alternate module APIs
by Flexx (Pilgrim) on Sep 09, 2002 at 22:08 UTC |