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I tried to make a simple module:

# Autoattr.pm package Autoattr; our $DEBUG; sub new($) { $DEBUG and printf STDERR "%s::new(%s)\n", __PACKAGE__, join ', ', map "'$_'", @_; ref $_[0] ? bless {%{$_[0]}}, ref $_[0] : bless {}, $_[0]; } sub DESTROY { $DEBUG and printf STDERR "%s::DESTROY(%s)\n", __PACKAGE__, join ', ', map "'$_'", @_; return; } sub AUTOLOAD { no strict qw(refs); our $AUTOLOAD; $DEBUG and printf STDERR "%s::AUTOLOAD=%s(%s)\n", __PACKAGE__, $AUTOLOAD, join ', ', map "'$_'", @_; if ($AUTOLOAD =~ /:get_([^:]*)$/) { my $attr = $1; *{$AUTOLOAD} = sub {$_[0]->{$attr}}; } elsif ($AUTOLOAD =~ /:set_([^:]*)$/) { my $attr = $1; *{$AUTOLOAD} = sub {$_[0]->{$attr} = $_[1]; $_[0]}; } else { (my $get = $AUTOLOAD) =~ s/([^:]*)$/get_$1/; (my $set = $AUTOLOAD) =~ s/([^:]*)$/set_$1/; *{$AUTOLOAD} = sub {goto \&{$#_ ? $set : $get}}; } goto \&$AUTOLOAD; } 1;
And use it thusly:
#!/usr/bin/perl -w package Foo; use base qw(Autoattr); sub get_foo {$_[0]->{foo} .= 'foo'} sub set_bar {$_[0]->{bar} = 'bar' x $_[1]; $_[0]} package Bar; use base qw(Foo); package main; BEGIN {$Autoattr::DEBUG = 1} $_ = Bar->new; printf "\n>>> %s, %s, %s\n\n", $_->foo, $_->foo, $_->foo; printf "\n>>> %s, %s, %s\n\n", do {$_->bar(3); $_->bar}, do {$_->bar(2); $_->bar}, do {$_->bar(1); $_->bar};

The idea was to somewhat emulate def foo and def bar= from Ruby.

If I use $_ = Foo->new, everything works as expected.

Autoattr::new('Foo') + Autoattr::AUTOLOAD=Foo::foo('Foo=HASH(0x225140)') + + >>> foo, foofoo, foofoofoo + + Autoattr::AUTOLOAD=Foo::bar('Foo=HASH(0x225140)', '3') + Autoattr::AUTOLOAD=Foo::get_bar('Foo=HASH(0x225140)') + >>> barbarbar, barbar, bar + + Autoattr::DESTROY('Foo=HASH(0x225140)')

However, with $_ = Bar->new as above, it no longer works.

Autoattr::new('Bar') + Autoattr::AUTOLOAD=Bar::foo('Bar=HASH(0x225164)') + Autoattr::AUTOLOAD=Bar::get_foo('Bar=HASH(0x225164)') + Use of uninitialized value in printf at C:\dev\perl\test.pl line 32. + Use of uninitialized value in printf at C:\dev\perl\test.pl line 32. + Use of uninitialized value in printf at C:\dev\perl\test.pl line 32. + + >>> , , + + Autoattr::AUTOLOAD=Bar::bar('Bar=HASH(0x225164)', '3') + Autoattr::AUTOLOAD=Bar::set_bar('Bar=HASH(0x225164)', '3') + Autoattr::AUTOLOAD=Bar::get_bar('Bar=HASH(0x225164)') + >>> 3, 2, 1 + + Autoattr::DESTROY('Bar=HASH(0x225164)')

To me, it seems like bouncing back out of &AUTOLOAD doesn't return to into traversing @ISA, which is sad. :-(

Am I misinterpreting something, and is there a better way of doing this? I don't want to have to (pre)declare all of the attributes that I'll be using.


Update:

Now I understand a little better.

If I call $_->Bar::foo, that does not ever get translated into $_->Foo::foo, regardless of @ISA.

Now that I understand that only ->foo has magic, and not ->Bar::foo, it makes fixing the problem easy.

Update^2:

Silly me.  UNIVERSAL::can returns exactly what I wanted: a "magical" code ref that follows inheritance when you call it, so I changed my code to use it.

package Autoattr; our $DEBUG; sub new($) { $DEBUG and printf STDERR "%s::new(%s)\n", __PACKAGE__, join ', ', map "'$_'", @_; ref $_[0] ? bless {%{$_[0]}}, ref $_[0] : bless {}, $_[0]; } sub DESTROY { $DEBUG and printf STDERR "%s::DESTROY(%s)\n", __PACKAGE__, join ', ', map "'$_'", @_; return; } sub AUTOLOAD { no strict qw(refs); $DEBUG and printf STDERR "%s::AUTOLOAD=%s(%s)\n", __PACKAGE__, our $AUTOLOAD, join ', ', map "'$_'", @_; *{$AUTOLOAD} = # into the symbo +l table $AUTOLOAD =~ /(?<![^:])get_([^:]*)$/s ? do { # define a gette +r my $attr = $1; sub($) {ref $_[0] ? $_[0]->{$attr} : ${"$_[0]::$attr"}}; } : $AUTOLOAD =~ /(?<![^:])set_([^:]*)$/s ? do { # define a sette +r my $attr = $1; sub($$) { ref $_[0] ? $_[0]->{$attr} : ${"$_[0]::$attr"} = $_[1] +; $_[0]; }; } : do { # get/set depend +ing on @_ (my $get = $AUTOLOAD) =~ s/([^:]*)$/get_$1/; (my $set = $AUTOLOAD) =~ s/([^:]*)$/set_$1/; sub($;$) {$#_ ? $_[0]->$set(@_[1 .. $#_]) : $_[0]->$get}; } ; $AUTOLOAD =~ /([^:]*)$/; goto $_[0]->can($1); # go to the new +symbol }

Thanks!


In reply to AUTOLOAD not following @ISA as expected [solved] by chibiryuu

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