.\" -*- mode: troff; coding: utf-8 -*- .\" Automatically generated by Pod::Man v6.0.2 (Pod::Simple 3.45) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. .ie n \{\ . ds C` "" . ds C' "" 'br\} .el\{\ . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" .\" Required to disable full justification in groff 1.23.0. .if n .ds AD l .\" ======================================================================== .\" .IX Title "Moose::Cookbook::Roles::Restartable_AdvancedComposition 3" .TH Moose::Cookbook::Roles::Restartable_AdvancedComposition 3 2026-06-15 "perl v5.42.2" "User Contributed Perl Documentation" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH NAME Moose::Cookbook::Roles::Restartable_AdvancedComposition \- Advanced Role Composition \- method exclusion and aliasing .SH VERSION .IX Header "VERSION" version 2.4000 .SH SYNOPSIS .IX Header "SYNOPSIS" .Vb 2 \& package Restartable; \& use Moose::Role; \& \& has \*(Aqis_paused\*(Aq => ( \& is => \*(Aqrw\*(Aq, \& isa => \*(AqBool\*(Aq, \& default => 0, \& ); \& \& requires \*(Aqsave_state\*(Aq, \*(Aqload_state\*(Aq; \& \& sub stop { 1 } \& \& sub start { 1 } \& \& package Restartable::ButUnreliable; \& use Moose::Role; \& \& with \*(AqRestartable\*(Aq => { \& \-alias => { \& stop => \*(Aq_stop\*(Aq, \& start => \*(Aq_start\*(Aq \& }, \& \-excludes => [ \*(Aqstop\*(Aq, \*(Aqstart\*(Aq ], \& }; \& \& sub stop { \& my $self = shift; \& \& $self\->explode() if rand(1) > .5; \& \& $self\->_stop(); \& } \& \& sub start { \& my $self = shift; \& \& $self\->explode() if rand(1) > .5; \& \& $self\->_start(); \& } \& \& package Restartable::ButBroken; \& use Moose::Role; \& \& with \*(AqRestartable\*(Aq => { \-excludes => [ \*(Aqstop\*(Aq, \*(Aqstart\*(Aq ] }; \& \& sub stop { \& my $self = shift; \& \& $self\->explode(); \& } \& \& sub start { \& my $self = shift; \& \& $self\->explode(); \& } .Ve .SH DESCRIPTION .IX Header "DESCRIPTION" In this example, we demonstrate how to exercise fine\-grained control over what methods we consume from a role. We have a \f(CW\*(C`Restartable\*(C'\fR role which provides an \f(CW\*(C`is_paused\*(C'\fR attribute, and two methods, \&\f(CW\*(C`stop\*(C'\fR and \f(CW\*(C`start\*(C'\fR. .PP Then we have two more roles which implement the same interface, each putting their own spin on the \f(CW\*(C`stop\*(C'\fR and \f(CW\*(C`start\*(C'\fR methods. .PP In the \f(CW\*(C`Restartable::ButUnreliable\*(C'\fR role, we want to provide a new implementation of \f(CW\*(C`stop\*(C'\fR and \f(CW\*(C`start\*(C'\fR, but still have access to the original implementation. To do this, we alias the methods from \&\f(CW\*(C`Restartable\*(C'\fR to private methods, and provide wrappers around the originals (1). .PP Note that aliasing simply \fIadds\fR a name, so we also need to exclude the methods with their original names. .PP .Vb 7 \& with \*(AqRestartable\*(Aq => { \& \-alias => { \& stop => \*(Aq_stop\*(Aq, \& start => \*(Aq_start\*(Aq \& }, \& \-excludes => [ \*(Aqstop\*(Aq, \*(Aqstart\*(Aq ], \& }; .Ve .PP In the \f(CW\*(C`Restartable::ButBroken\*(C'\fR role, we want to provide an entirely new behavior for \f(CW\*(C`stop\*(C'\fR and \f(CW\*(C`start\*(C'\fR. We exclude them entirely when composing the \f(CW\*(C`Restartable\*(C'\fR role into \f(CW\*(C`Restartable::ButBroken\*(C'\fR. .PP It\*(Aqs worth noting that the \f(CW\*(C`\-excludes\*(C'\fR parameter also accepts a single string as an argument if you just want to exclude one method. .PP .Vb 1 \& with \*(AqRestartable\*(Aq => { \-excludes => [ \*(Aqstop\*(Aq, \*(Aqstart\*(Aq ] }; .Ve .SH CONCLUSION .IX Header "CONCLUSION" Exclusion and renaming are a power tool that can be handy, especially when building roles out of other roles. In this example, all of our roles implement the \f(CW\*(C`Restartable\*(C'\fR role. Each role provides same API, but each has a different implementation under the hood. .PP You can also use the method aliasing and excluding features when composing a role into a class. .SH FOOTNOTES .IX Header "FOOTNOTES" .IP (1) 4 .IX Item "(1)" The mention of wrapper should tell you that we could do the same thing using method modifiers, but for the sake of this example, we don\*(Aqt. .SH AUTHORS .IX Header "AUTHORS" .IP \(bu 4 Stevan Little .IP \(bu 4 Dave Rolsky .IP \(bu 4 Jesse Luehrs .IP \(bu 4 Shawn M Moore .IP \(bu 4 יובל קוג\*(Aqמן (Yuval Kogman) .IP \(bu 4 Karen Etheridge .IP \(bu 4 Florian Ragwitz .IP \(bu 4 Hans Dieter Pearcey .IP \(bu 4 Chris Prather .IP \(bu 4 Matt S Trout .SH "COPYRIGHT AND LICENSE" .IX Header "COPYRIGHT AND LICENSE" This software is copyright (c) 2006 by Infinity Interactive, Inc. .PP This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.