Getting started

Install the library

You can choose to download lastest Deval release or build it from source.

Option 1: download latest release

Download latest Deval release, unzip it somewhere inside your project directory and skip to next section to see how to import Deval into your project.

Option 2: build from source

You’ll need following requirements to build Deval from source:

Install Node.js & npm, clone Deval repository, browse to cloned directory and run npm install command to install dependencies and build:

$ git checkout
$ cd deval
$ npm install

Once build, copy content of the src folder somwhere in your project and move to next section.

Import into your project

Require file deval.php file to start using the library ; here is a minimal code example that shows most common features. Save the snippet below into some sample.php file, we’ll dig into details about each line in next sections:


require 'lib/deval/deval.php';

// Create a new renderer for template file 'template/users.deval' and use
// directory 'cache' to store pre-evaluated intermediate results (your web
// user must have read/write permission on this directory)
$renderer = new Deval\CacheRenderer('template/users.deval', 'cache/');

// Inject some standard functions into template e.g. 'find', 'sort', etc.

// Inject compile-time constants that will be used for pre-evaluation. Only
// serializable values can be used here, see API documentation about the
// inject method for more details
$renderer->inject(array('language' => 'en-us'));

// Inject render-time variables and print rendered output
echo $renderer->render(array('users' => array('Jane', 'John')));

In this example we created an instance of Deval\CacheRenderer which is a production renderer able to cache pre-evaluated code for optimal performance. You may also want to put performance aside, for example when developing your project, and use a Deval\FileRenderer instead that won’t cache anything and reprocess your templates on each call, or even a Deval\StringRenderer that will let you specify your template code as a string instead of reading it from a file:

// Create a simple file-based renderer with no caching optimization
$renderer = new Deval\FileRenderer('template/users.deval');

// Create a string-based renderer, still with no caching
$renderer = new Deval\StringRenderer($my_template_code);

By default you don’t have access to PHP functions from within a template (we’ll explain why exactly in Functional constraint section), which is why we added a first call to method Deval\Renderer::inject in previous example. It’s here to inject a few common functions in our template and make them available before compilation to enable many early optimizations. A full list of functions injected from Deval\Builtin::deval can be found in the functions section.

Write a template

Now you’re ready for writing a template. Create a new text file in your favorite editor and type in some contents:

Note: this page should be displayed using {{ $ language }} locale.

Users list: {{ $ join(", ", users) }}

Save this file as template/users.deval (relative to your previously created sample.php file) to match the name we used in previous example. Don’t forget to create a cache/ directory to store pre-evaluated results and browse to your sample.php file. Result should look like this:

Note: this page should be displayed using en-us locale.

Users list: Jane, John

As you can guess the join function we used in our template is one of the builtin ones we mentionned earlier, and is similar to PHP’s standard implode function.

One last note before jumping into more details: if you’re curious you can have a look at the content of your cache/ folder, it should now contain a .php file generated from your template. Edit this file and see the note about page locale includes a literal en-us part which has been pre-evaluated since it was injected as a constant. The users variable however still exists and is expected to be provided at rendering. If you change your sample code and switch language value to "fr-fr" (or anything different from "en-us") then display the page again, you’ll see a second generated file appearing in cache/ folder to store this second pre-evaluated variant of your template.

Now you have all the basics, continue to next section to read about language syntax and how to write real-life templates.