template

		<{$variable|func:$(0),param1,param2,...}> is available(we can use this is array loop)
	description
		$variable
			the variable we want to operate with.e.g. we assign a variable in the controller "$this->assign('variable',$variable)" or we assign an array
			$this->assign('arr',array('one','two','three'));
			then we can use it in the template 
			eg.tpl
				<{loop $arr $variable}>
					<{$variable|substr:$(0),1,2}>
				<{ /loop }>
		|
			this is the delimiter between the target variable and function
		func
			the function we want to effect the $variable.
			we can use an internal function like substr() or we can use a outer function,for example,we define a function in /commons/functions.inc.php
				function color($tar,$color){
					return ''.$tar.'';
				}
			the most important thing is that the function is available(have been included)
		:
			the delimiter between function and parameters
		$(0)
			this is the placeholder of the $variable(position is not fixed,we can place it any where depending on the need).that's to say,it's value is $variable
			one thing we should notice is,we should not enclose it with single or double quotes
		param1,param2,...
			the function parameters list.
			if it is a string,single or double quote are encouraged