Plesk Extensions API stubs is a set of files with all classes
definitions and methods prototypes, but without implementation of these
methods. You can use API stubs for quicker development.
The first step is to checkout the API stubs repository. It’s located at
https://github.com/plesk/pm-api-stubs. You need to check out stubs to a
separate directory (do not mix with extension’s source code). Later you
can use these stubs for all extension projects you’ve started. If you
have no Git client for checkout, download a zip archive and unpack it –
https://github.com/plesk/pm-api-stubs/archive/master.zip.
Note: The repository https://github.com/plesk/pm-api-stubs contains API
stubs for latest released Plesk version. API stubs for older versions
are placed in separate branches.
Next step is to configure an IDE (for example, PhpStorm) to include the
stubs as an external library. Please see the details in the Plesk
developers blog in the article: Extensions: IDE and APIs
Hinting.
As a result, if you open a file with source code and start typing the
code, completion of API methods and classes will start working and you
do not need to to check API documentation at every step.