156 lines
3.4 KiB
Perl
156 lines
3.4 KiB
Perl
#============================================================= -*-Perl-*-
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#
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# Template::Plugin::Assert
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#
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# DESCRIPTION
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# Template Toolkit plugin module which allows you to assert that
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# items fetches from the stash are defined.
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#
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# AUTHOR
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# Andy Wardley <abw@wardley.org>
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#
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# COPYRIGHT
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# Copyright (C) 2008 Andy Wardley. All Rights Reserved.
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#
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# This module is free software; you can redistribute it and/or
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# modify it under the same terms as Perl itself.
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#
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#============================================================================
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package Template::Plugin::Assert;
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use base 'Template::Plugin';
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use strict;
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use warnings;
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use Template::Exception;
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our $VERSION = '3.009';
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our $MONAD = 'Template::Monad::Assert';
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our $EXCEPTION = 'Template::Exception';
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our $AUTOLOAD;
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sub load {
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my $class = shift;
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my $context = shift;
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my $stash = $context->stash;
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my $vmethod = sub {
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$MONAD->new($stash, shift);
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};
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# define .assert vmethods for hash and list objects
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$context->define_vmethod( hash => assert => $vmethod );
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$context->define_vmethod( list => assert => $vmethod );
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return $class;
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}
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sub new {
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my ($class, $context, @args) = @_;
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# create an assert plugin object which will handle simple variable
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# lookups.
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return bless { _CONTEXT => $context }, $class;
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}
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sub AUTOLOAD {
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my ($self, @args) = @_;
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my $item = $AUTOLOAD;
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$item =~ s/.*:://;
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return if $item eq 'DESTROY';
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# lookup the named values
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my $stash = $self->{ _CONTEXT }->stash;
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my $value = $stash->dotop($stash, $item, \@args);
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if (! defined $value) {
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die $EXCEPTION->new( assert => "undefined value for $item" );
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}
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return $value;
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}
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package Template::Monad::Assert;
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our $EXCEPTION = 'Template::Exception';
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our $AUTOLOAD;
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sub new {
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my ($class, $stash, $this) = @_;
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bless [$stash, $this], $class;
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}
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sub AUTOLOAD {
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my ($self, @args) = @_;
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my ($stash, $this) = @$self;
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my $item = $AUTOLOAD;
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$item =~ s/.*:://;
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return if $item eq 'DESTROY';
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my $value = $stash->dotop($stash, $item, \@args);
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if (! defined $value) {
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die $EXCEPTION->new( assert => "undefined value for $item" );
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}
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return $value;
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}
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1;
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__END__
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=head1 NAME
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Template::Plugin::Assert - trap undefined values
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=head1 SYNOPSIS
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[% USE assert %]
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# throws error if any undefined values are returned
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[% object.assert.method %]
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[% hash.assert.key %]
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[% list.assert.item %]
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=head1 DESCRIPTION
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This plugin defines the C<assert> virtual method that can be used
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to automatically throw errors when undefined values are used.
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For example, consider this dotop:
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[% user.name %]
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If C<user.name> is an undefined value then TT will silently ignore the
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fact and print nothing. If you C<USE> the C<assert> plugin then you
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can add the C<assert> vmethod between the C<user> and C<name> elements,
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like so:
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[% user.assert.name %]
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Now, if C<user.name> is an undefined value, an exception will be thrown:
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assert error - undefined value for name
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=head1 AUTHOR
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Andy Wardley E<lt>abw@wardley.orgE<gt> L<http://wardley.org/>
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=head1 COPYRIGHT
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Copyright (C) 2008 Andy Wardley. All Rights Reserved.
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This module is free software; you can redistribute it and/or
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modify it under the same terms as Perl itself.
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=head1 SEE ALSO
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L<Template::Plugin>
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=cut
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# Local Variables:
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# mode: perl
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# perl-indent-level: 4
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# indent-tabs-mode: nil
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# End:
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#
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# vim: expandtab shiftwidth=4:
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