.\" -*- mode: troff; coding: utf-8 -*- .\" Automatically generated by Pod::Man 5.0102 (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 .\" ======================================================================== .\" .IX Title "Moose::Cookbook::Basics::Document_AugmentAndInner 3pm" .TH Moose::Cookbook::Basics::Document_AugmentAndInner 3pm 2025-01-04 "perl v5.40.0" "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::Basics::Document_AugmentAndInner \- The augment modifier, which turns normal method overriding "inside\-out" .SH VERSION .IX Header "VERSION" version 2.2207 .SH SYNOPSIS .IX Header "SYNOPSIS" .Vb 2 \& package Document::Page; \& use Moose; \& \& has \*(Aqbody\*(Aq => ( is => \*(Aqrw\*(Aq, isa => \*(AqStr\*(Aq, default => sub {\*(Aq\*(Aq} ); \& \& sub create { \& my $self = shift; \& $self\->open_page; \& inner(); \& $self\->close_page; \& } \& \& sub append_body { \& my ( $self, $appendage ) = @_; \& $self\->body( $self\->body . $appendage ); \& } \& \& sub open_page { (shift)\->append_body(\*(Aq<page>\*(Aq) } \& sub close_page { (shift)\->append_body(\*(Aq</page>\*(Aq) } \& \& package Document::PageWithHeadersAndFooters; \& use Moose; \& \& extends \*(AqDocument::Page\*(Aq; \& \& augment \*(Aqcreate\*(Aq => sub { \& my $self = shift; \& $self\->create_header; \& inner(); \& $self\->create_footer; \& }; \& \& sub create_header { (shift)\->append_body(\*(Aq<header/>\*(Aq) } \& sub create_footer { (shift)\->append_body(\*(Aq<footer/>\*(Aq) } \& \& package TPSReport; \& use Moose; \& \& extends \*(AqDocument::PageWithHeadersAndFooters\*(Aq; \& \& augment \*(Aqcreate\*(Aq => sub { \& my $self = shift; \& $self\->create_tps_report; \& inner(); \& }; \& \& sub create_tps_report { \& (shift)\->append_body(\*(Aq<report type="tps"/>\*(Aq); \& } \& \& # <page><header/><report type="tps"/><footer/></page> \& my $report_xml = TPSReport\->new\->create; .Ve .SH DESCRIPTION .IX Header "DESCRIPTION" This recipe shows how the \f(CW\*(C`augment\*(C'\fR method modifier works. This modifier reverses the normal subclass to parent method resolution order. With an \f(CW\*(C`augment\*(C'\fR modifier the \fIleast\fR specific method is called first. Each successive call to \f(CW\*(C`inner\*(C'\fR descends the inheritance tree, ending at the most specific subclass. .PP The \f(CW\*(C`augment\*(C'\fR modifier lets you design a parent class that can be extended in a specific way. The parent provides generic wrapper functionality, and the subclasses fill in the details. .PP In the example above, we've created a set of document classes, with the most specific being the \f(CW\*(C`TPSReport\*(C'\fR class. .PP We start with the least specific class, \f(CW\*(C`Document::Page\*(C'\fR. Its create method contains a call to \f(CWinner()\fR: .PP .Vb 6 \& sub create { \& my $self = shift; \& $self\->open_page; \& inner(); \& $self\->close_page; \& } .Ve .PP The \f(CW\*(C`inner\*(C'\fR function is exported by \f(CW\*(C`Moose\*(C'\fR, and is like \f(CW\*(C`super\*(C'\fR for augmented methods. When \f(CW\*(C`inner\*(C'\fR is called, Moose finds the next method in the chain, which is the \f(CW\*(C`augment\*(C'\fR modifier in \&\f(CW\*(C`Document::PageWithHeadersAndFooters\*(C'\fR. You'll note that we can call \&\f(CW\*(C`inner\*(C'\fR in our modifier: .PP .Vb 6 \& augment \*(Aqcreate\*(Aq => sub { \& my $self = shift; \& $self\->create_header; \& inner(); \& $self\->create_footer; \& }; .Ve .PP This finds the next most specific modifier, in the \f(CW\*(C`TPSReport\*(C'\fR class. .PP Finally, in the \f(CW\*(C`TPSReport\*(C'\fR class, the chain comes to an end: .PP .Vb 5 \& augment \*(Aqcreate\*(Aq => sub { \& my $self = shift; \& $self\->create_tps_report; \& inner(); \& }; .Ve .PP We do call the \f(CW\*(C`inner\*(C'\fR function one more time, but since there is no more specific subclass, this is a no-op. Making this call means we can easily subclass \f(CW\*(C`TPSReport\*(C'\fR in the future. .SH CONCLUSION .IX Header "CONCLUSION" The \f(CW\*(C`augment\*(C'\fR modifier is a powerful tool for creating a set of nested wrappers. It's not something you will need often, but when you do, it is very handy. .SH AUTHORS .IX Header "AUTHORS" .IP \(bu 4 Stevan Little <stevan@cpan.org> .IP \(bu 4 Dave Rolsky <autarch@urth.org> .IP \(bu 4 Jesse Luehrs <doy@cpan.org> .IP \(bu 4 Shawn M Moore <sartak@cpan.org> .IP \(bu 4 יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org> .IP \(bu 4 Karen Etheridge <ether@cpan.org> .IP \(bu 4 Florian Ragwitz <rafl@debian.org> .IP \(bu 4 Hans Dieter Pearcey <hdp@cpan.org> .IP \(bu 4 Chris Prather <chris@prather.org> .IP \(bu 4 Matt S Trout <mstrout@cpan.org> .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.