Creating a plugin inside a namespace

By using a namespace, everything inside the namespace does not need globally unique naming prefixes, solving clashing issues with other plugins, themes and wordpress itself. Using a namespace is much simpler than using a class for your plugin.

Add all your php files to the namespace

Add this to the top of each file

<?php
namespace MyPluginName;

Every function or class defined in this file will be considered as part of this namespace

WordPress hooks, Shortcodes, etc

You must include your namespace in the definition, e.g.

add_action( 'wp_enqueue_scripts', '\MyPluginName\my_function_name' );
//add_filter('wp_enqueue_scripts', __NAMESPACE__ . '\my_function_name');    <<<Alternative method
function my_function_name()
{
}

add_shortcode('my_shortcode', '\MyPluginName\my_shortcode_function');
function my_shortcode_function()
{
}

Using plugin define values

$MyValue = \MyPluginName\MY_PLUGIN_DEFINE;

Calling Functions

Functions in a file under the same namespace

You can call it directly

WordPress functions

If you don’t have a function with the same name under your namespace then you can call it directly.

Forcibly specifying that the function is in the global space:

  $post_id = \wp_insert_post();

Functions in another namespace (and calling functions in your plugin from outside the plugin)

You need to specify the namespace:

$Result = \SomeOtherNamespace\function_name();

If you want to define the other namespaces function a being used within this namespace you can use:

use function SomeOtherNamespace\function_name;

//Now your can use that function directly
$Result = function_name();

Functions using the same name in your namespace and also not in any namespace

How a call to function foo() is resolved – calling from inside the namespace:
1) It looks for a function from the current namespace call foo().
2) If that fails it tries to find and call the global function foo().

How a call to function foo() is resolved – calling from outside the namespace:
It tries to find and call the global function foo().

Defines

By default define() defines a constant in the global namespace, even if used in a file that is part of a specific namespace.

To define a constant for use inside a namespace you need to prefix the constant name with the namespace:

define(__NAMESPACE__ . "\MY_CONSTANT_NAME",          24);

//Which is the same as:
define("MyNamespaceName\MY_CONSTANT_NAME",          24);

Use of the define within the namespace doesn’t require the prefex, just the definition does.