Text::Xslate::Manual::Debugging(3pm)

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NAME

6       Text::Xslate::Manual::Debugging - Debugging techniques for Xslate
7       templates
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DESCRIPTION

10       This document describes techniques for debugging templates.
11
12   Setting "verbose => 2"
13       Try "verbose => 2" in the first step. This option enables full
14       warnings, especially warnings related to "undef".
15
16   File names and line numbers
17       Xslate messages include file names, line numbers, and, if possible,
18       source code lines which seems problems.
19
20       You can also access the file name and the line number in templates by
21       "__FILE__" and "__LINE__" tokens just like as Perl.
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23       If you want reports files and lines from your registered functions,
24       "Text::Xslate->current_file" and "Text::Xslate->current_line" in
25       callbacks are the same as "__FILE__" and "__LINE__" in templates
26       respectively.
27
28           sub my_sqrt {
29               my($n) = @_;
30
31               if($n < 1) {
32                   # return a message instead of warnings
33                   return sprintf "!!! Can't take sqrt of $n at %s line %d !!!",
34                       Text::Xslate->current_file, Text::Xslate->current_line;
35               }
36               return sqrt($n);
37           }
38
39           my $tx = Text::Xslate->new(
40               function => { sqrt => \&my_sqrt },
41           );
42
43   To dump values
44       You can use any dumping modules via the "function" option, but Xslate
45       has a builtin "dump" filter to dump template values.
46
47           <: $value | dump # Dump $value with Data::Dumper :>
48
49   Detection of missing variables (or typos or variable names)
50       Xslate itself has warning system for use of uninitialized values, but
51       sometimes it is not enough.
52
53       If you want fill in some string, e.g. FILL ME, for missing variables,
54       you can use the "hash_with_default()" utility. For example:
55
56           use Text::Xslate::Util qw(hash_with_default);
57           $tx->render($name, hash_with_default(\%vars, sub { "FILL ME '@_' " }) );
58
59       Note that this is really slow because it is a tied-hash wrapper.
60
61   Customization of error messages
62       You can customize error handlers by "warn_handler" and "die_handler".
63       In these handlers, you can call "Text::Xslate->print()" method in order
64       to add your custom messages to the output buffer, which makes debugging
65       easier.
66
67           #!perl -w
68           use strict;
69           use Text::Xslate;
70           my %vpath = (
71               hello => 'Hello, <: $lang :> world!' . "\n",
72           );
73           my $tx = Text::Xslate->new(
74               path         => \%vpath,
75               verbose      => 2,
76               warn_handler => sub { Text::Xslate->print('[[', @_, ']]') },
77           );
78
79           print $tx->render('hello', { });
80           # => Hello, [[use nil to print at ...]] world!
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NAME

DESCRIPTION

SEE ALSO