What are the real advantages of templating engines over just using PHP?
I develop my web applications using only PHP for the view files and I don't feel limited in any way, but I hear there's a consistent number of developers advocating "external" templating engines. So what do template engines offer that simple PHP lacks?
I'm looking for practical things, so I exclude the following:
- babysitting bad developers (i.e. use a template engine because it forces you to not mix code into presentation)
- conciseness of syntax (I have mappings in Vim for things like
<?php echo $stuff; ?>, using curly braces wouldn't make any difference) - easier syntax for non programmers (I develop alone so that's not an issue)
Answer
New Syntax
Some people wont agree, but since I've been using Twig the "for ... else" feels right. It might not be a lot, but it keeps my templates that little bit cleaner.
{% for row in articles %}
Display articles ...
{% else %}
No articles.
{% endfor %}
Automatic Escaping
You can have the template engine automatically escape any output. This is great as you no longer have to repeat htmlspecialchars ... everywhere. Twig does this nicely.
{% autoescape on %}
Everything will be automatically escaped in this block
{% endautoescape %}
Template Inheritance
Another feature I like is the ability to extend base templates. Here's a basic example
base.html template
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang="en">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
{% block head %}
<link rel="stylesheet" href="style.css" />
<title>{% block title %}{% endblock %} - My Webpage</title>
{% endblock %}
</head>
<body>
<div id="content">{% block content %}{% endblock %}</div>
<div id="footer">
{% block footer %}
© Copyright 2009 by <a href="http://domain.invalid/">you</a>.
{% endblock %}
</div>
</body>
child.html template
{% extends "base.html" %}
{% block title %}Index{% endblock %}
{% block head %}
{% parent %}
<style type="text/css">
.important { color: #336699; }
</style>
{% endblock %}
{% block content %}
<h1>Index</h1>
<p class="important">
Welcome on my awesome homepage.
</p>
{% endblock %}
A child template can override blocks for page specific styles, content, etc ... You can also notice the use of {% parent %} which grabs the parents content so you don't lose it all while overriding.
I recommend you give Twig a go. Extremely useful.