Smarty 3 Overview

Rewritten for PHP 5

The Smarty 3 code base is a 100% rewrite, and contains many language features that do not exist in PHP 4. This means Smarty 3 will NOT work with PHP 4. If you need PHP 4 support, you will have to stick with Smarty 2 until you can upgrade PHP.

Design Goal

Smarty's fundamental design goal remains the same: To separate application code from the presentation. This implies that PHP is separated from the presentation. A detailed explanation of why this is important can be found here.

New Lexer/Parser

Smarty has a new template parser, a real syntax lexer. This gives Smarty much finer control over its template syntax. Things like in-template math, line-precision error messages and recursive template functions are now possible.

Template Objects

You can now make template objects and execute them independently. Example:

PHP

$tpl = $smarty->createTemplate('my.tpl');
$tpl->assign('foo','bar');
$smarty->display($tpl); // or $tpl->display();

Data Objects

The variables assigned to a template can now be managed independently as a Smarty_Data object. Example:

PHP

$data = new Smarty_Data;
$data->assign('foo','bar');
$smarty->display('my.tpl',$data);
$tpl = $smarty->createTemplate('my.tpl',$data);

PHP Streams

You can now use PHP Streams as data sources for components of Smarty. If you call:

PHP

$smarty->display('foo:bar.tpl');

or in a template call:

Smarty

{include file="foo:bar.tpl"}

Smarty will first look for a registered template resource named foo. If nothing is found, it will check if a PHP stream is available. If foo://bar is available, Smarty will use it to fetch the template. You can also use streams to call variables. {$foo:bar} will use the foo://bar stream to get the template variable.

Template Inheritance

Templates can now inherit from each other. You mark blocks of a template with {block name=foo}{/block} tags, a template can inherit with the {extend file="my.tpl"} tag, and then you can replace, change or append the blocked contents from the inheriting template(s). Example:

parent .tpl

<html>
  <head>
  	<title>{block name=title}default title{/block}<title>
  </head>
  <body>
	{block name=body}default body{/block}
  </body>
</html>

child .tpl

{extends file="parent.tpl"}
{block name=title}My Child Title{/block}
{block name=body}My Child Body{/block}

output of $smarty->display('child.tpl');

<html>
  <head>
  	<title>My Child Title<title>
  </head>
  <body>
	My Child Body
  </body>
</html>

See more here.

"{" and "}" (Javascript) Auto-Escapement

In Smarty 2, you had to escape occurances of {} characters by surrounding them with {literal}{/literal} blocks or replacing them with {ldelim}{rdelim} tags. With Smarty 3, the braces will be ignored so long as they are surrounded by white space.

javascript

<script>
   // the following braces are ignored by Smarty
   // since they are surrounded by whitespace
   function foobar {
	alert('foobar!');
   }
   // this one will need literal escapement
   {literal}
	function bazzy {alert('foobar!');}
   {/literal}
</script>

Variable Filters

The default template modifier feature of Smarty 2 has been replaced with variable filters. A variable filter can be applied to the output of template variables globally. We have pre, post, and output filters, now we have a fourth choice: 'variable'. When you apply the filter such as:

PHP

$smarty->registerFilter('variable','htmlspecialchars');

then all output from variables is HTML escaped. You can also selectively disable this in-line with {$foo nofilter}.

In-Template Function Definitions

You can create functions within a template and call them just like a plugin function. When you have a plugin that generates presentational content, keeping it in the template is often a more manageable choice. It also simplifies data traversal, such as deeply nested menus. Example:

Smarty

{* define the function *}
{function name=menu level=0}
  <ul class="level{$level}">
  {foreach $data as $entry}
    {if is_array($entry)}
      <li>{$entry@key}</li>
      {menu data=$entry level=$level+1}
    {else}
      <li>{$entry}</li>
    {/if}
  {/foreach}
  </ul>
{/function}

{* create an array to demonstrate *}
{$menu = ['item1','item2','item3' => ['item3-1','item3-2','item3-3' =>
['item3-3-1','item3-3-2']],'item4']}

{* run the array through the function *}
{menu data=$menu}

Output

* item1
* item2
* item3
      o item3-1
      o item3-2
      o item3-3
            + item3-3-1
            + item3-3-2
* item4

Precision Caching

You can now specify items to be non-cached inline such as {$foo nocache} or {include file="foo.tpl" nocache}

Backward-Compatibility with Smarty 2

Much of Smarty 3 is backward compatible with Smarty 2, except for the items noted in the SMARTY2_BC_NOTES file included with the Smarty 3 distribution. Please see that file for a detail breakdown of BC differences.

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