What is an application?¶

One of the important things to understand when you learn Lino is the Site class. A Site represents an application.

An application, for Lino, is a standalone piece of software that is perceived as an entity by end-users.

An application program (app or application for short) is a computer program designed to perform a group of coordinated functions, tasks, or activities for the benefit of the user. -- Wikipedia

Django comes with a rather special use of the word 'application'. Daniel and Audrey (Two scoops of Django) say it in a diplomatic way: "It's not uncommon for new Django developers to become understandably confused by Django's usage of the word 'app'." But to be honest: Django is simply wrong at this point. It says "application" where it should say "plugin" or "module". Things like django.contrib.contenttypes are not what normal people would call an "application", they are rather "plugins" or "modules".

That said, we will of course forgive Django this oddness, which has understandable historical reasons. After all it is basically just a vocabulary problem. Many Django people are more or less aware of that problem, but it would be really much work to fix it because the word is used in variables like app_label and INSTALLED_APPS. Too much work for "just a vocabulary" problem.

The "only" problem with this vocabulary problem is that it leaves us (Lino developers) with no word left for what we would want to call an application. A Lino application is neither an "app" nor a "project".

That's why we chose Site as the name for the class which describes an application (as Lino understands it), and the Plugin class as a wrapper for what Django calls "applications".

Lino's Plugin class is comparable to Django's AppConfig class, but has some additional features, which makes them the preferred way.