Autoload for your classes, interfaces and traits by WordPress Coding Standard.
composer require wppunk/wpautoload
Then add to the composer.json:
{
...
"extra": {
"wp-autoload": {
"\\Name\\Space\\": "src"
}
},
...
}
Where key it is namespace and value it is the folder name.
namespace My_Plugin
path src inside the plugin my-plugin.
Names for class, interface, trait:
wppunk\My_Plugin\Core\Awesome_Feature
wppunk\My_Plugin\Admin\Interface_Awesome_Feature
wppunk\My_Plugin\Front\Trait_Awesome_Feature
Paths:
.../wp-content/plugins/my-plugin/src/core/class-awesome-feature.php
.../wp-content/plugins/my-plugin/src/admin/interface-awesome-feature.php
.../wp-content/plugins/my-plugin/src/front/trait-awesome-feature.php