Usage of Template Engine

• push-style (with pull methods for e.g. csrf & i18n) lazy topo-ordered
• incremental building liberated from von neumann style applicative

1. https://en.wikipedia.org/wiki/Template_processor
2. Separates visual code (HTML/CSS) from logic code (PHP).

1. parent file -> associated template
2. how do templates work
3. concept and internals
4. $tpl->naming
5. how to process conditions
6. how to use filters

1. action/example.php
2. action/template/example.tpl

1. templatest.php^[link1]
2. templatestescaper.php^[link2]
3. templatestfilters.php^[link3]
4. templatestsetter.php^[link4]
5. templatestuser.php^[link5]

1. _cache/template
2. action/template
3. formatter/highlight/template
4. handler/page/template
5. theme/_common
6. theme/default/appearance/template

1. Workflow

2. Base File

 $tpl->variable = $value;	

2.1. Setting and leaving prefixes

$tpl->enter('menu_');

$tpl->leave();	

2.2. Assign template definition to variable

$message = $tpl->definitionName();

$message->mode		= $this->_t('RenamePage');
$message->log_l_message	= $record['value'];

$this->set_message($message, 'success');	

[ == definitionName == ]
<strong>[ ' mode ' ]</strong>
[ ' log ' ]

[ === log === ]
<ul>
	[= l _ =
		<li>[ ' message ' ]</li>
	=]
</ul>	

2.3. Hints

2.3.1. Line endings

2.3.2. Array building

2.3.3. Assign arrays

<?php

$colors = ['blue', 'green', 'red', 'yellow'];

foreach ($colors as $color)
{
    $tpl->n_color = $color;
}
	

<ul>
    [= n _ =
        <li>[ ' color ' ]</li>
    =]
</ul>

3. Template File

simple example template

[ === main === ]
	[ ' variable ' ]	

3.1. Syntax

3.1.1. Include

3.1.2. Definitions

[ === DefinitionTwo === ]
[ ' im DefinitionOne ' ] [ ' title ' ]
[ === DefinitionOne === ]
<img src="[ ' db: theme_url ' ]icon/spacer.png" alt="[ ' title ' ]">	

3.1.3. Inline definitions

[ = abc def =
   ...
 = ]	

3.1.4. Variables

3.1.5. Pull

[ ' pull: value ' ]	

3.2. Filters

 [ ' variable | filter1 | filter2 | ... ' ]	

3.3. Examples

3.4. Hints

Warning: Creating default object from empty value in ...	

3.5. Filter Chains

 [ ' variable | filter1 | filter2 | ... ' ]	

4. Write your own templates

4.1. cheat sheet

[ '  ' ]
[ ' _t:  ' ]
[ ' db:  ' ]
[ ' href: ' ]
[ '  | checkbox ' ]
[ '  | check 0 ' ]
[ '  | number 0 , . ' ]
[ '  | number_format ' ]
[ '  | time_format ' ]
[ '  | pre ' ]
[ '  | e ' ]
[ '  | e attr ' ]

[=  _ =

=]

<form action="[ ' href: add_handler ' ]" method="post" name="add_name">
	[ ' csrf: add_name ' ]

<option value="[ ' id ' ]" [ ' sel | list "" 'selected ' ' ]>[ ' mode ' ]</option>

$tpl->enter('prefix_');
$tpl->leave();	

[= l _ =
	<li>
		<a href="[ ' href ' ]" class="tag" rel="tag">[ ' category | e ' ]</a>
	</li>
=]

[ '' l link '' ]

[ === link === ]
<li>
	<a href="[ ' href ' ]" class="tag" rel="tag">[ ' category | e ' ]</a></li>
</li>	

5. open issues

5.1. next line issue for textarea and pre

1. Templatest strips all \n line breaks from [ ' body ' ] which is in this case undesired. We need all \n line breaks in body for POST or action include.
2. Additional the auto-indent feature may add \t.
   1. e.g. in form <input type="hidden" name="body" value="multi line body"> , one should not serve HTML in PHP file and pass it as $tpl->kludge = HTML;

1. show handler (body may have a pre field)
2. _comment handler (body -> textarea)
3. edit handler (body -> textarea)
4. permissions handler (list field holding privileges -> textarea)
5. filemeta handler (file caption -> textarea)
6. include action (body -> pre)
7. news action (body -> pre)

$tpl->include	= $this->action('include', ['page' => '/' . $page['tag'], 'notoc' => 0, 'nomark' => 1], true);	

$tpl->body		= $body; // Ut::html($body)
echo '<textarea>' . Ut::html($body) . "</textarea>\n";	

• hotfix, handlers
• use [ ' data | pre ' ], add NO additional filter, run HTML escaping Ut::html($data); prior in the PHP file if you have to