Enough about Classes, Let's Talk Templates

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Jonathan Reinink Software developer from Canada Been writing PHP for
about 15 years Marketing agency for over a decade Started contract development this year Leadership group of The PHP League Wrote the Plates template library Wrote the Glide image library I <3 open source

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Why do templates matter?

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Templates often account for 25-50% of your overall code base.

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Templates help separate your controller and domain logic from your
presentation logic.

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None

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Templates are often developed by both server-side developers, and front-end
developers.

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Templates are always "spaghetti code". Because contain more than one
language in the same ﬁle.

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Bad template code contributes to technical debt.

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Step 1: Choose the right template library.

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People have very strong opinions about templating.

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“This blog post is not for the faint- hearted! Some
people will strongly disagree with me and some others will probably want to kill me at the upcoming Zend Conference.” —Fabien Potencier

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“I'm not suggesting that native PHP templates are better than
compiled templates (like Twig).” —Me

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“oh... puts the pitchfork down” —Friendly Reddit reader “hides torch
behind back…” —Another friendly Reddit reader

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The native PHP vs compiled templates debate.

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PHP is the oldest method of templating in PHP. (because
PHP is a templating language)

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<html> ! <h1>Hello, <?=$name?></h1> ! <ul> <?php if ($stmt =
$mysqli->prepare("SELECT name FROM friends")) { $stmt->execute(); $stmt->bind_result($name); ! while ($stmt->fetch()) { echo '<li>'.$name.'</li>'; } } ?> </ul>

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Important lesson: If your templates contain SQL code, you’re doing
it wrong.

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While PHP has evolved into a mature, object oriented language,
it hasn’t improved much as a templating language.

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Compiled templates ﬁll this void by offering a new syntax
speciﬁcally geared for templating.

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{% extends "template.html" %} ! {% block title %}User Profile{%
endblock %} ! {% block content %} <h1>User Profile</h1> <p>Hello, {{ name }}</p> {% endblock %}

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Since these compiled templates must be compiled, there is a
slight performance hit.

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You can write good template code with most modern templating
libraries. Twig, Blade, Smarty, Moustache, Plates, Aura.View, Zend\View, etc…

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I recommend you use Twig.

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Choose a templating language with an easy learning curve. Easy
for both server-side developers and front-end developers.

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Compiled languages offer very simple, template oriented syntax. {{ var
}}

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<?php if ($items): ?> <?php foreach ($items as $item): ?>
<li><?php echo $item ?></li> <?php endforeach ?> <?php else: ?> <li>No items found.</li> <?php endif ?> {% for item in items %} <li>{{ item }}</li> {% else %} <li>No items found.</li> {% endfor %} Native PHP Twig

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But, native PHP templates don’t have to be ugly.

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Always use the short echo syntax. <?php echo $name; ?>
<?=$user->name?>

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Never use blocks of PHP. <?php foreach ($users as $user)
{ echo $user->name; } ?> <?php foreach ($users as $user): ?> <?=$user->name?> <?php endforeach ?>

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Only one statement per PHP tag. <?php if ($users) {
foreach ($users as $user) { ?> <?=$user->name?> <?php } } ?> <?php if ($users): ?> <?php foreach ($users as $user): ?> <?=$user->name?> <?php endforeach ?> <?php endif ?>

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Never use curly brackets. <?php foreach ($users as $user) {
?> <?=$user->name?> <?php } ?> <?php foreach ($users as $user): ?> <?=$user->name?> <?php endforeach ?>

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Never using semicolons. <?php echo $name; ?> <?=$user->name?>

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<?php $this->layout('template', ['title' => 'User Profile']) ?> ! <h1>Hello <?=$this->e($name)?></h1>
! <h2>Friends</h2> <ul> <?php foreach($friends as $friend): ?> <li> <a href="/profile/<?=$this->e($friend->id)?>"> <?=$this->e($friend->name)?> </a> </li> <?php endforeach ?> </ul> ! <?php if ($invitations): ?> <h2>Invitations</h2> <p>You have some friend invites!</p> <?php endif ?>

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Avoid XML attribute based templating languages.

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<div class="item" tal:repeat="value values"> <div class="title"> <span tal:condition="value/hasDate" tal:replace="value/getDate"/> <a
tal:attributes="href value/getUrl" tal:content="value/getTitle"/> </div> <div id="content" tal:content="value/getContent"/> </div>

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Choose a templating language with syntax highlighting and auto- completion
in your editor of choice.

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Always, always, always escape unsafe data.

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Hello, <?=$name?>

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Hello, Jonathan

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Hello, <a href="http://xssattack.com/">Click here</a>

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Hello, <a href="http://xssattack.com/ ">Click here</a>gt;

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Hello, <a href="http://xssattack.com/">Click here</a>

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Hello, <?=htmlspecialchars($name, ENT_QUOTES | ENT_SUBSTITUTE)?>

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Hello, <?=$this->escape($name)?> Hello, <?=$this->e($name)?> Hello, <?=e($name)?>

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1. HTML escaping 2. HTML attribute escaping 3. CSS escaping
4. JavaScript escaping 5. URL escaping Be aware of the different types of escaping:

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If at all possible, use automatic escaping!

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Hello, {{ name }}

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Without automatic escaping, you MUST manually escape every single variable.
And you will probably forget once in a while!!!

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It should also be VERY obvious in your templates when
you are outputting raw data.

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Hello, {!! $name !!} Hello, {{ name|raw }} Blade Twig

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Automatic escaping is NOT possible in native PHP.

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<h1><?=$this->name?></h1> Attempt 1: Object overloading

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class Template { protected $values; ! public function __get($name) {
return $this->escape( $this->values[$name] ); } }

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Problem: How do you escape object params and method calls?
<h1><?=$this->user->name?></h1>

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Attempt 2: Object overloading with proxies <h1><?=$this->user->name?></h1>

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class Template { protected $values; ! public function __get($name) {
return new TemplateProxy( $this->values[$name] ); } }

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class TemplateProxy { protected $value; ! public function __get($name) {
return new TemplateProxy($this->name); } ! public function __call($name, $args) { return new TemplateProxy(...); } ! public function __toString() { return $this->escape($this->value); } }

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<h1><?=$this->user->name?></h1>

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None

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Problems: double escaping, poor performance, horrible error debugging, collisions with
template methods, etc, etc.

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Attempt 3: Compiled native php templates

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<h1><?=$name?></h1> <h1><?=$this->escape($name)?></h1> Pre-compilation: Post-compilation:

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None

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Automatic escaping is NOT possible in native PHP.

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Watch your whitespace, this isn’t the Wild Wild West.

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Always use tabs, or always use spaces, NEVER MIX.

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Watch your indenting.

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<ul> {% for item in items %} <li>{{ item }}</li>
{% else %} <li>No items found.</li> {% endfor %} </ul>

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Use comments that only appear in the template, not the
rendered markup.

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{# This is a Twig comment #}

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Your templates should be very low on logic.

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Templates are not responsible for data lookup, persistence or other
complex tasks.

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Anything outside of conditionals, loops and basic formatting is a
code smell.

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Watch your control structures. Use: if, for, foreach Don’t use:
switch, while, do-while

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So what exactly is basic formatting then? • Date formatting
• Case changes • String concatenation • String trimming • Number formatting • URL encoding

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Consider using a logic- less templating language.

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<ul> {{# users }} <li>{{ name }}</li> {{/ users }}
</ul>

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namespace App\ViewModels; ! class UsersViewModel { public function users() {
return [ ['name' => 'Jonathan'], ['name' => 'Amy'], ['name' => 'Joey'], ]; } }

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Some template logic is okay, but only if it’s presentation
logic.

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Avoid accessing the global namespace.

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@if (Request::is('/')) <a class="active" href="/">Home</a> @else <a href="/">Home</a> @endif

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@if ($url === '/') <a class="active" href="/">Home</a> @else <a href="/">Home</a>
@endif

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Preassign template data instead of accessing global variables.

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$templates->addData(['url' => $url], 'header');

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view()->composer('header', function ($view) { $view->with('url', $url); });

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$twig->addGlobal('url', $url);

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Use the dot notation for variable resolution. object.parameter Access arrays,
objects and methods the same way.

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{{ user.name }} = $user['name'] {{ user.name }} = $user->name
{{ user.name }} = $user->name()

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Templates should only know about one instance variable.

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Rule #4: Controllers can instantiate only one object. Therefore, views
can only know about one instance variable and views should only send messages to that object. — Sandi Metz, rules for developers

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Keep your templates as short as possible. Break templates into
smaller, reusables pieces.

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<?php $this->insert('partials/header') ?> ! <p>Your page content.</p> ! <?php $this->insert('partials/footer')
?>

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<?php $this->insert('partials/header', ['title' => 'Home']) ?> ! <p>Your page content.</p>
! <?php $this->insert('partials/footer') ?>

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{% include 'partials/header.html' with {'title': 'Home'} %} ! <p>Your page
content.</p> ! {% include 'partials/footer.html' %}

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Don't be afraid to repeat (very) small pieces of code.

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<select> <?php foreach ($users as $user): ?> <option <?php if
($current_user === $user) echo 'selected' ?> value="<?=$user->id?>"> <?=$user->name?> </option> <?php endforeach ?> </select>

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<select> <?php foreach ($users as $user): ?> <?php if ($current_user
=== $user): ?> <option selected value="<?=$user->id?>"><?=$user->name?></option> <?php else ?> <option value="<?=$user->id?>"><?=$user->name?></option> <?php endif ?> <?php endforeach ?> </select>

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Use inheritance for even better organization of templates.

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template.html {% extends "template.html" %} ! {% block title %}Profile{%
endblock %} {% block content %} <h1>Profile</h1> <p>Hello, {{ name }}</p> {% endblock %} proﬁle.html <html> <head> <title> {% block title %} Default title {% endblock %} </title> </head> <body> ! <main> {% block content %} <p>Default content</p> {% endblock %} </main> ! </body> </html>

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Use a templating language that you can extend.

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$templates->registerFunction('upper', function ($string) { return strtoupper($string); }); <h1>Hello <?=$this->upper($name)</h1>

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Blade::directive('datetime', function ($expression) { return "<?php echo with{$expression}->format('m/d/Y H:i'); ?>";
}); @datetime($blog->publish_date)

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Use a template language that’s easy to debug.

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Use a template language that offers a sandbox mode.

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Use a template language that performs well. Hint: they basically
all do.

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Automatic escaping is WAY more important than the speed advantage
of native PHP templates.

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Follow me on Twitter at @reinink Rate this talk joind.in/15753
Thanks!

Enough about Classes, Let's Talk Templates

Enough about Classes, Let's Talk Templates

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