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{eval}

{eval} is used to evaluate a variable as a template. This can be used for things like embedding template tags/variables into variables or tags/variables into config file variables.

If you supply the assign attribute, the output of the {eval} function will be assigned to this template variable instead of being output to the template.

Attribute Name Type Required Default Description
var mixed Yes n/a Variable (or string) to evaluate
assign string No n/a The template variable the output will be assigned to

Technical Note

  • Evaluated variables are treated the same as templates. They follow the same escapement and security features just as if they were templates.

  • Evaluated variables are compiled on every invocation, the compiled versions are not saved! However if you have caching enabled, the output will be cached with the rest of the template.

  • If the content to evaluate doesn't change often, or is used repeatedly, consider using {include file="string:{$template_code}"} instead. This may cache the compiled state and thus doesn't have to run the (comparably slow) compiler on every invocation.

Example 135. {eval}

The contents of the config file, setup.conf.


emphstart = <strong>
emphend = </strong>
title = Welcome to {$company}'s home page!
ErrorCity = You must supply a {#emphstart#}city{#emphend#}.
ErrorState = You must supply a {#emphstart#}state{#emphend#}.

  

Where the template is:


{config_load file='setup.conf'}

{eval var=$foo}
{eval var=#title#}
{eval var=#ErrorCity#}
{eval var=#ErrorState# assign='state_error'}
{$state_error}

  

The above template will output:


This is the contents of foo.
Welcome to Foobar Pub & Grill's home page!
You must supply a <strong>city</strong>.
You must supply a <strong>state</strong>.

  

Example 136. Another {eval} example

This outputs the server name (in uppercase) and IP. The assigned variable $str could be from a database query.


 
<?php
$str 
'The server name is {$smarty.server.SERVER_NAME|upper} '
       
.'at {$smarty.server.SERVER_ADDR}';
$smarty->assign('foo',$str);
?>
 
   

Where the template is:

 
    {eval var=$foo}
 
   

Smarty Template Engine