access to var from template in php before compile - php

Question

I want in template file can limit count of result, something like this :
file.tpl
{$box_count = 10}
{foreach $box}
.
.
.
{/foreach}
how can i handle and get this variables in php to limit result in database ?
example :
<?php
$smarty = new Smarty;
$count = ... //HOW CAN GET ?
$data = array();
$q = mysql_query( "SELECT * FROM `users` LIMIT 0,$count" );
while( $r = mysql_fetch_array( $q ) )
{
$data[] = $r;
}
$smarty->assign( 'box' , $data );
$smarty->dipslay( 'file.tpl' );
?>
note :
because this var just defined in tpl file, in getTemplateVars() not exists .
thanks

Answer 1

i solved this problem with registerObject :
<?php
$smarty = new Smarty;
class Test
{
public function setCount( $params , &$smarty )
{
$count = $params['count'];
$data = array();
$q = mysql_query( "SELECT * FROM `users` LIMIT 0,$count" );
while( $r = mysql_fetch_array( $q ) )
{
$data[] = $r;
}
$smarty->assign( 'box' , $data );
}
}
$S = new Test;
$smarty->registerObject( 'Test' , $S , array( 'setCount' ) )
$smarty->dipslay( 'file.tpl' );
?>
file.tpl :
{Test->setCount count="10"}
{foreach $box}
.
.
.
{/foreach}