Moo From Hell #1: How to proxy a sub from a non OO module [SOLVED]

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

Hi all,

here is what did:

The role:

package Utils;

use URI;
use List::MoreUtils qw(uniq);
use Types::Standard qw(InstanceOf);
use Moo::Role;

requires qw(list monks);

sub my_uniq {
    my $self   = shift;
    my @result = uniq @{ $self->list };
    wantarray ? @result : scalar @result;
}

has 'uri' => (
    is      => 'lazy',
    isa     => InstanceOf ['URI'],
    default => sub { my $self = shift; URI->new( $self->monks ) },
    handles => [qw(host)],
);

1;

__END__
[download]

The class:

package Karl;

use Types::Standard qw(ArrayRef Str);
use Moo;

has list  => ( is => 'lazy', isa => ArrayRef );
has monks => ( is => 'lazy', isa => Str );

with qw(Utils);

1;

__END__
[download]

And the script:

#!/usr/bin/env perl

use strict;
use warnings;
use feature qw(say);
use Data::Dump;
use Karl;

my $monks   = qq(http://www.perlmonks.org);
my $list = [qw(cuke cuke)];
my $nose = Karl->new( list => $list, monks => $monks );

dd $nose;

my $uniq = $nose->my_uniq;
say $uniq;

my @uniq = $nose->my_uniq;
say for @uniq;

say $nose->host;

__END__
[download]

This works as expected and i hope that it is good practice. OK, i'm a bit unsure about this :-(

But i wonder how to handle the call to uniq like the call to host.

I would like to say $nose->uniq, instead of $nose->my_uniq.

In other words: how can i proxy (or delegate) a sub from a non OO module?

I must admit that i'm a bit confused for the moment.

Best regards and thank you very much for any hint, Karl

ŤThe Crux of the Biscuit is the Apostropheť

Comment on Moo From Hell #1: How to proxy a sub from a non OO module [SOLVED] Select or Download Code

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Re: Moo From Hell #1: How to proxy a sub from a non OO module by AnomalousMonk (Archbishop) on Aug 02, 2015 at 17:16 UTC
I can't test this ATM, it's just a guess, but why not something like: `package Utils; ...; use List::MoreUtils (); # note empty optional import list ...; ...; sub uniq { my $self = shift; # fully qualify List::MoreUtils function my @result = List::MoreUtils::uniq @{ $self->list }; wantarray ? @result : scalar @result; } ... 1; # And the script: ... use Karl; ... ... my $uniq = $nose->uniq; ...` [download] Update: (Update: And a bit OT:) Does Moo interfere with the propagation of context in some way I'm not aware of? If not, the return statement of `my_uniq()` in the OPed code `wantarray ? @result : scalar @result;` would seem to return exactly what would be returned anyway in list or scalar context by just returning an array, i.e., the same as a `return @result;` statement. It makes no particular difference, but I was just curious. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re^2: Moo From Hell #1: How to proxy a sub from a non OO module by karlgoethebier (Abbot) on Aug 02, 2015 at 18:06 UTC
"...why not something like..." Yes sure. I tried i already. Because of... `karls-mac-mini:MyMoo karl$ ./run.pl Prototype mismatch: sub Utils::uniq (@) vs none at Utils.pm line 20. Compilation failed in require at /Users/karl/perl5/perlbrew/perls/perl +-5.20.0threads/lib/site_perl/5.20.0/Module/Runtime.pm line 317. Compilation failed in require at ./run.pl line 7. BEGIN failed--compilation aborted at ./run.pl line 7.` [download] ...what i don't understand (for the moment). OK, I should have mentioned it...sorry. Best regards and thanks for advice, Karl ŤThe Crux of the Biscuit is the Apostropheť	[reply] [d/l]
Re^3: Moo From Hell #1: How to proxy a sub from a non OO module by BrowserUk (Patriarch) on Aug 02, 2015 at 18:19 UTC
Prototype mismatch: sub Utils::uniq (@) vs none at Utils.pm line 20. You're importing uniq() and then redefining it; hence the error. Instead, don't import it: `use List::MoreUtils ();` [download] Then call it fully qualified: `my @result = List::MoreUtils::uniq @{ $self->list };` [download] Anyone got any experience of this phone's predecessor? With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice. I'm with torvalds on this Agile (and TDD) debunked I told'em LLVM was the way to go. But did they listen!	[reply] [d/l] [select]
Re^4: Moo From Hell #1: How to proxy a sub from a non OO module by karlgoethebier (Abbot) on Aug 02, 2015 at 18:47 UTC
Re^5: Moo From Hell #1: How to proxy a sub from a non OO module by Your Mother (Archbishop) on Aug 02, 2015 at 20:16 UTC
Some notes below your chosen depth have not been shown here
Re^2: Moo From Hell #1: How to proxy a sub from a non OO module by karlgoethebier (Abbot) on Aug 02, 2015 at 18:12 UTC
"...Does Moo interfere with the propagation of context in some way..." I guess it doesn't. Same behavior without `wantarray`. Regards, Karl ŤThe Crux of the Biscuit is the Apostropheť	[reply] [d/l]
Re: Moo From Hell #1: How to proxy a sub from a non OO module [SOLVED] by Monk::Thomas (Friar) on Aug 03, 2015 at 08:58 UTC
(This is unrelated to your actual question / problem.) Why do you use wantarray? `sub my_uniq { my $self = shift; my @result = uniq @{ $self->list }; wantarray ? @result : scalar @result; }` [download] Why don't you simply write `sub my_uniq { my $self = shift; return uniq @{ $self->list }; }` [download] My guess is it's a performance optimization since it reimplements already existing behaviour. Have you benchmarked it? My personal opinion - feel free to ignore it. As far as I can see the method my_uniq is simply a convenience function to make it easier to work with the array reference stored in the field 'list'. I would design the class differently and not provide any direct access to the field 'list' at all. Instead provide an accessor which returns the list as an array and drop the convenience function 'my_uniq'. `# class method sub get_list { my $self = shift; return @{ $self->list() }; }` [download] `# client code - variant a # (client wants values and count) my @uniq_list = uniq $obj->get_list(); my $uniq_count = scalar @uniq_list; # client code - variant b # (client just wants the count) my $uniq_count = scalar uniq $obj->get_list();` [download] Main reason: If the user wants to do something else with the list (e.g. reverse) then I don't need to reimplement these functions too.	[reply] [d/l] [select]
Re^2: Moo From Hell #1: How to proxy a sub from a non OO module [SOLVED] by AnomalousMonk (Archbishop) on Aug 03, 2015 at 11:52 UTC
This is unrelated to your actual question / problem. But this reply bears upon the question of organization or factoring of code, which is closely related to the OPed question. ++ from me. My personal opinion - feel free to ignore it. The section advising use of a list getter for member data so that normal list processing functions can be used on the data makes me wish I could ++ again. Ignore this advice if you will, but you do so at your own peril! Give a man a fish: `<%-(-(-(-<`	[reply] [d/l]