Let Template.php Eat Static

04.14.2007

My arch-nemisis is overly complex logic in template.php and page.tpl.php files. It seems to me that when a drupal codebase becomes brittle and unmaintainable, the culprit is usually going to be hundreds of conditional lines of php code in a template file. You've probably seen code like this before:

THEMES/SPAGETTI_MONSTER/TEMPLATE.PHP

<?php

The dangers of this approach are something that cannot be explained: they must be felt first hand.

Switching args in a template.php or page.tpl.php file is like doing drugs (minus the laughs): lots of people have done it, survived, and even learned from it; but its an experience that is best avoided if you can help it. So lets see how to avoid it using static variables. (warning, you'll need to use a module).

SPAGETTI_MONSTER_KILLER.MODULE

<?php
function spagetti_monster_killer_set_body_class($class = NULL) {
  // set the variable to static 
  static $set_class;
  // if a class has been given, then go ahead and set it
  if ($class) {
    $set_class = $class; 
  }
  if (!$set_class) {
    // return a default class
    $set_class = 'random_page';
  }
  // now return it
  return $set_class;
}
function spagetti_monster_killer_nodeapi(&$node, $op, $teaser, $page) {
  switch ($op) {
    case 'view':
      if ($page == TRUE) {
        // indeed..... this is clearly a page view of a node -- set the template.php body class 'node_page'....
        spagetti_monster_killer_set_body_class('node_page'); 
      }
      break; 
  }
}

function spagetti_monster_killer_form_alter($form_id, &$form) { if ($form['#id'] == 'node-form') { // we are absolutely certain we are viewing a node form... gee-wiz spagetti_monster_killer_set_body_class('node_edit'); } } ?>

Its not hard to see why this approach allows more freedom, more maintainability, more modularity, less maintaince, and less opprotunity to make a mistake. Its likely to be a more efficent too since the class just gets set when certain functions execute (such as node_view($node, FALSE, TRUE)), instead of having to walk through a long switch statement. Using this method, all you have to have in template.php is this:

<?php
function spagetti_monster_page($content) {
  // simply use a null vallue so that the function returns whatever was last in memory. In otherwords, anywhere this function ran to generate a page will determine the value. Give static a try....
  $body_class = spagetti_monster_killer_set_body_class(NULL); 
}
?>

A final note that these examples scratch the surface of this concept. Many people will perhaps shun such an approach -- I'd like to hear their reasons. I am, after all, an idiot.

Nick Lewis's blog

Comments

Mon, 2007-08-06 19:32 — a passing drifter (not verified)

Hi, This looks like a great

Hi,

This looks like a great code but I'm searching the Net for answers because I'm not that good at PHP yet.

Can you please give some more examples of ways to target specific pages?

I need to add a classname to the body when a view called 'services' is being viewed.

Thanks!

Sat, 2007-04-14 17:06 — dldege@drupal.org (not verified)

Similar Approach

I was just recently shown a similar approach of using a static to simplify my template.php code. While this function still requires looking at args() is does simply my other logic.

<?php
function circ_get_node_type() {
  static $type;
  
  if (!$type) {
    if (arg(0) == 'node' && is_numeric(arg(1))) {
      $node = node_load(arg(1));
      $type = $node->type;
    }
    else
      $type = '';
  }
  
  return $type;
}
?>

Then in other template.php theme overrides and what not.

<?php
function circ_breadcrumb($breadcrumb) {
  if (circ_get_node_type() == 'file' || circadia_get_node_type() == 'folder')
    $variables = array('breadcrumb' => implode('/', $breadcrumb));
  else
    $variables = array('breadcrumb' => implode(' :: ', $breadcrumb));
  return _phptemplate_callback('breadcrumb', $variables, array('breadcrumb'));
}
?>

I see good uses for your approach as well.

Sat, 2007-04-14 16:35 — merlinofchaos (not verified)

A patch for core in 6.0

I have a core patch for Drupal 6 to add this kind of feature so that a lot of the grunt work of doing this will be automagic.

It doesn't, however, have a great deal of traction yet. Maybe you can help!

http://drupal.org/node/113382

Sat, 2007-04-14 07:03 — chx (not verified)

Some minor notes. You want

Some minor notes. You want if (isset($class)) the default value can be set as static $stored_class = 'default'; and I usually prefer to have a get function function spagetti_monster_killer_set_body_class() {return spagetti_monster_killer_set_body_class();}

If you change the setter later then the you do not need to change the get. It helps.

Otherwise yes, you shall do this.