Get Twig.

Use Twig.

Smile.

Talk by
@codekipple Carl Hughes

Illustration by
@laurasuzanneillustration

What is Twig? 🤷

Template engine for PHP
Built by Sensio Labs the company responsible for Symfony
Stand alone component
Can and is being used in many different framewoks and applications

What is a template engine? 🤷‍♂️

Separates backend code (PHP) from the presentation layer (HTML).
Provides concise syntax for doing common template logic.

Why use one? 🙋🏿

HTML more readable, PHP is cumbersome, when mixed with HTML it makes both the PHP and the HTML harder to read.
Template orientated syntax with shortcuts for common patterns
Can be used to create reusable templates/patterns.
Security, automatic output escaping can be enabled
Because it's really fun.

Code examples

<?php echo $var ?>
<?php echo htmlspecialchars($var, ENT_QUOTES, 'UTF-8') ?>

{{ var }}
{{ var|escape }}
{{ var|e }}         {# shortcut to escape a variable #}

PHP way

Twig way 😍

escaping

Code examples

<?php if ($posts): ?>
    <?php foreach ($posts as $post): ?>
        <?php echo $post['title']; ?>
    <?php endforeach; ?>
<?php else: ?>
    <p>Sorry, no posts matched your criteria.<p>
<?php endif; ?>

{% for post in posts %}
    {{ post.title }}
{% else %}
    <p>Sorry, no posts matched your criteria.</p>
{% endfor %}

Looping

PHP way

Twig way 😍

OK! but how to use it with WordPress? 🙋🏽

There's a plugin for that

Not all Hero's wear capes
Jared Novack started the Timber plugin
Plugin handles of the integration between
Twig and Wordpress plus adds a host of extra
WordPress specific functionality to Twig.
https://en-gb.wordpress.org/plugins/timber-library/

Timber starter Theme

https://github.com/timber/starter-theme
Based on the Underscores theme _s

How does it affect theming? 🙋🏿‍♂️

"Because WordPress is awesome, but the_loop isn't."
- https://github.com/timber/timber

PHP files no longer contain any HTML.
No more the_loop!

"

- Me

"

Let's create a theme

All example code can be found here

https://github.com/codekipple/twig-wordcamp-bristol-2017

Structure HTML - PHP way

<!doctype html>
<html <?php language_attributes(); ?>>
<head>
    <!-- header meta -->
</head>
<body class="{{ body_class }}">

    <header class="page-head">
        <div class="logo" role="banner">
            <a href="<?php bloginfo( 'url' ); ?>" rel="home"><?php bloginfo( 'name' ); ?></a>
        </div>
    </header>

    <main role="main">

    </main>

    <footer class="page-foot">
        <div class="u-constrict u-clearfix">
            <div class="footer-text">
                <p>Copyright <?php echo date('Y'); ?></p>
            </div>
        </div>
    </footer>

    <?php wp_footer(); ?>
</body>
</html>

header.php

page.php

<?php get_header(); ?>

<div class="main-content">
    <!-- page content -->
</div>

<?php get_footer(); ?>

footer.php

Structure HTML - Twig way

No more header.php of footer.php!*
Everything goes into the base template
Define blocks whose content can be:-
- Replaced
- Appended to
- Prepended to

* With the caveat that some plugins need header.php and footer.php but this can be dealt with, see files in timber starter theme https://github.com/timber/starter-theme

Twig has template inheritance, all templates that extend the base template can remove or redefine the blocks within it.

Structure HTML - Twig way 😍

<!doctype html>
<html {{ site.language_attributes }}>
<head>{% include 'partials/head.twig' %}</head>
<body class="{{ body_class }}" data-template="base.twig">
    {% block header %}
        <header class="page-head">
            <div class="logo" role="banner"><a href="{{site.url}}" rel="home">{{site.name}}</a></div>
        </header>
    {% endblock %}
    
    {% block main %}
    <main role="main">
        <div class="main-content">
            {% block content %}
                Sorry, no content
            {% endblock %}
        </div>
    </main>
    {% endblock %}

    {% block footer %}
        <footer class="page-foot">
            {% block footer_content %}
                <div class="footer-text">
                    <p>Copyright {{ "now"|date('Y') }}</p>
                </div>
            {% endblock %}
        </footer>
        {{ function('wp_footer') }}
    {% endblock %}
</body>
</html>

templates/base.twig

Structure HTML - Twig way 😍

templates/page.twig

{% extends "base.twig" %}

{% block content %}
    <p>Page content</p>
{% endblock %}

Working with {% blocks %}

templates/base.twig

Replace content

Append to contents

Prepend to contents

Remove block

{% block sidebar %}
    <p>Content</p>
{% endblock %}

{% block sidebar %}
    {{ parent() }}
    <p>content</p>
{% endblock %}

{% block sidebar %}
    <p>content</p>
    {{ parent() }}
{% endblock %}

{% block sidebar false %}

Check block exists

{% if block("sidebar") is defined %}
    <p>Content</p>
{% endif %}

index.php - Old way

<?php get_header(); ?>

<div class="main-content">
    <?php if ( have_posts() ) : ?>
        <h2>Latest posts</h2>

        <?php while ( have_posts() ) : the_post(); ?>
            <h2><a href="<?php echo esc_url( get_permalink() ) ?>"><?php the_title(); ?></a></h2>
            <?php the_content() ?>
        <?php endwhile; ?>
    <?php endif; ?>
</div>

<?php get_footer(); ?>

page.php

Uses the_loop, looks compact but if we start adding custom content other than the latest posts (e.g. a custom post type) the template can get quite verbose.

index.php - Twig way

<?php

// get global context
$context = Timber::get_context();

// Gets post retrieved from WordPress and 
// add them to $context array
$context['posts'] = Timber::get_posts(); 

// render the template and pass the $context
Timber::render( array( 'index.twig' ), $context );

The responsibility of index.php becomes to fill the $context with all the data the template needs.

This is going to return an object with a lot of the common things we need across the site (navs, current theme, theme url, site name...)

index.php

index.php - Twig way 😍

{% extends "base.twig" %}

{% block content %}
    <h2>Latest posts</h2>
    {% for post in posts %}
        <article class="post post-{{post.post_type}}" id="post-{{post.ID}}">
            <h2><a href="{{ post.link }}">{{ post.title }}</a></h2>
            <p>{{ post.get_preview }}</p>
        </article>
    {% endfor %}
{% endblock %}

index.twig

index.twig extends the base twig template
Adds latest post to the content block

Theme progress

Ok out theme now has a homepage displaying the latest posts.

Lets add some Tweets

Appear in footer
Only on homepage

Tweets - PHP way

    </main>

    <footer class="page-foot">
        <div class="footer-text"><p>Copyright <?php echo date('Y'); ?></p></div>

        <?php 
        $tweets = get_tweets();

        if ($tweets && is_home()): ?>
            <div class="tweets">
                <h3>Tweets</h3>
                <ul>
                    <?php foreach ($tweets as $tweet): ?>
                        <li class="tweet">
                            <a href="<?php echo $tweet['link']; ?>">
                                <img src="<?php echo $tweet['avi']; ?>" alt="" />
                            </a>
                            <?php echo $tweet['tweet']; ?>
                        </li>
                    <?php endforeach; ?>
                </ul>
            </div>
        <?php endif; ?>
    </footer>
    <?php wp_footer(); ?>
</body>
</html>

footer.php

Tweets - Twig way

<?php
$context = Timber::get_context();
$context['posts'] = Timber::get_posts(); 
$context['tweets'] = get_tweets();
Timber::render( array( 'index.twig' ), $context );

index.php

Get tweet data
Add it to the $context array so it gets passed along to the index.twig template

Tweets - Twig way 😍

{% extends "base.twig" %}

{% block content %}
    <h2>Latest posts</h2>
    {% for post in posts %}
        <article class="post post-{{post.post_type}}" id="post-{{post.ID}}">
            <h2><a href="{{ post.link }}">{{ post.title }}</a></h2>
            <p>{{ post.get_preview }}</p>
        </article>
    {% endfor %}
{% endblock %}


{% block footer_content %}
    {{ parent() }}
    
    {% if tweets %}
        <div class="tweets">
            <h3>Tweets</h3>
            <ul>
                {% for post in posts %}
                    <li class="tweet">
                        <a href="{{ tweet.link }}">
                            <img src="tweet.avi" alt="" />
                        </a>
                        {{ tweet.text }}
                    </li>
                {% endfor %}
            </ul>
        </div>
    {% endif %}
{% endblock %}

index.twig

Theme progress

We will add them to the index and page template.
Structure of each widget will be the same.
Content of widgets will be different.

Lets add widgets

Widgets - PHP way

<?php $widgets = get_widgets(); ?>

<section class="homepage-widgets">
    <h2>Widgets</h2>

    <?php $i =0; foreach ($widgets as $widget): $i++; ?>
        <div class="widget">
            <h3><?php echo $widget['title']; ?></h3>
            <p><?php echo $widget['body']; ?></p>
        </div>
    <?php endforeach; ?>
</section>

<?php $widgets = get_widgets(); ?>

<section class="page-widgets">
    <?php $i =0; foreach ($widgets as $widget): $i++; ?>
        <div class="widget">
            <h3><?php echo $widget['title']; ?></h3>
            <p><?php echo $widget['body']; ?></p>
        </div>
    <?php endforeach; ?>
</section>

The widget components HTML is repeated.

index.php

page.php

Image the widget component was more complicated 😐

Now imagine it was included in 6 different page templates 😞

Widgets - Twig way 😍

<div class="homepage-widgets">
    <h2>Widgets</h2>
    {% for widget in widgets %}
        {% include 'partials/widget.twig' with {
            'title': widget.title,
            'body': widget.body
        } %}
    {% endfor %}
</div>

<div class="widget">
    <h3>{{ title }}</h3>
    <p>{{ body }}</p>
</div>

$context['tweets'] = get_tweets();

index.twig

index.php

partials/widget.twig

One widget component template that is used everywhere.

Twig include statement similar to the PHP include statement

Theme progress

Styleguide

If we have reusable Twig templates why not add a styleguide that runs off the same templates.
Spress is a static site generator that has Twig template support

Styleguide

When changing widget.twig both the site and styleguide are updated.

What about child themes? 🙋🏼‍♂️

Timber plugin looks for Twig templates in child theme first.
Works as you would expect.

Example themes

Twig - Uses Twig via Timber includes styleguide via Spress.

Child - Child of Twig theme

Normal - Same design as the Twig theme but no Twig.

https://github.com/codekipple/twig-wordcamp-bristol-2017

Get Twig.

Use Twig.

Smile.

What is Twig? 🤷

What is a template engine? 🤷‍♂️

Why use one? 🙋🏿

Code examples

Code examples

OK! but how to use it with WordPress? 🙋🏽

Timber starter Theme

How does it affect theming? 🙋🏿‍♂️

"

- Me

"

Let's create a theme

Structure HTML - PHP way

Structure HTML - Twig way

Structure HTML - Twig way 😍

Structure HTML - Twig way 😍

Working with {% blocks %}

index.php - Old way

index.php - Twig way

index.php - Twig way 😍

Theme progress

Lets add some Tweets

Tweets - PHP way

Tweets - Twig way

Tweets - Twig way 😍

Theme progress

Lets add widgets

Widgets - PHP way

Widgets - Twig way 😍

Theme progress

Styleguide

Styleguide

What about child themes? 🙋🏼‍♂️

Example themes

Thanks.

Any questions?

Get Twig. Use Twig. Smile

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