Article
Beyond The Template Engine
Template Class Source Code
And finally, the Template class.
<?php
/**
* Copyright (c) 2003 Brian E. Lozier (brian@massassi.net)
*
* set_vars() method contributed by Ricardo Garcia (Thanks!)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
class Template {
var $vars; /// Holds all the template variables
var $path; /// Path to the templates
/**
* Constructor
*
* @param string $path the path to the templates
*
* @return void
*/
function Template($path = null) {
$this->path = $path;
$this->vars = array();
}
/**
* Set the path to the template files.
*
* @param string $path path to template files
*
* @return void
*/
function set_path($path) {
$this->path = $path;
}
/**
* Set a template variable.
*
* @param string $name name of the variable to set
* @param mixed $value the value of the variable
*
* @return void
*/
function set($name, $value) {
$this->vars[$name] = $value;
}
/**
* Set a bunch of variables at once using an associative array.
*
* @param array $vars array of vars to set
* @param bool $clear whether to completely overwrite the existing vars
*
* @return void
*/
function set_vars($vars, $clear = false) {
if($clear) {
$this->vars = $vars;
}
else {
if(is_array($vars)) $this->vars = array_merge($this->vars, $vars);
}
}
/**
* Open, parse, and return the template file.
*
* @param string string the template file name
*
* @return string
*/
function fetch($file) {
extract($this->vars); // Extract the vars to local namespace
ob_start(); // Start output buffering
include($this->path . $file); // Include the file
$contents = ob_get_contents(); // Get the contents of the buffer
ob_end_clean(); // End buffering and discard
return $contents; // Return the contents
}
}
/**
* An extension to Template that provides automatic caching of
* template contents.
*/
class CachedTemplate extends Template {
var $cache_id;
var $expire;
var $cached;
/**
* Constructor.
*
* @param string $path path to template files
* @param string $cache_id unique cache identifier
* @param int $expire number of seconds the cache will live
*
* @return void
*/
function CachedTemplate($path, $cache_id = null, $expire = 900) {
$this->Template($path);
$this->cache_id = $cache_id ? 'cache/' . md5($cache_id) : $cache_id;
$this->expire = $expire;
}
/**
* Test to see whether the currently loaded cache_id has a valid
* corrosponding cache file.
*
* @return bool
*/
function is_cached() {
if($this->cached) return true;
// Passed a cache_id?
if(!$this->cache_id) return false;
// Cache file exists?
if(!file_exists($this->cache_id)) return false;
// Can get the time of the file?
if(!($mtime = filemtime($this->cache_id))) return false;
// Cache expired?
if(($mtime + $this->expire) < time()) {
@unlink($this->cache_id);
return false;
}
else {
/**
* Cache the results of this is_cached() call. Why? So
* we don't have to double the overhead for each template.
* If we didn't cache, it would be hitting the file system
* twice as much (file_exists() & filemtime() [twice each]).
*/
$this->cached = true;
return true;
}
}
/**
* This function returns a cached copy of a template (if it exists),
* otherwise, it parses it as normal and caches the content.
*
* @param $file string the template file
*
* @return string
*/
function fetch_cache($file) {
if($this->is_cached()) {
$fp = @fopen($this->cache_id, 'r');
$contents = fread($fp, filesize($this->cache_id));
fclose($fp);
return $contents;
}
else {
$contents = $this->fetch($file);
// Write the cache
if($fp = @fopen($this->cache_id, 'w')) {
fwrite($fp, $contents);
fclose($fp);
}
else {
die('Unable to write cache.');
}
return $contents;
}
}
}
?>
Another important thing to note about the solution presented here is that we pass the file name of the template to the fetch() method call. This can be useful if you want to re-use template objects without having to re-set() all the variables.
And remember: the point of template engines should be to separate your business logic from your presentation logic, not to separate your PHP code from your HTML code.