interfaces. How to implement?

Question

Yii

How to implement interfaces in yii2? And where do you store them anyway? I remember in yii1 there was a components directory, where you could write your own classes that were not related to either model or controller's.
ps: why such a question arose - I want to transfer this calendar extension from zend to yii2 ( https://github.com/SCLInternet/BmCalendar ).

Answer 1

Everywhere.
Some directories from 1.1 are missing. It is worth noting components, extensions, messages and migrations. The extensions directory is no longer needed. Extensions are installed through Composer and automatically get into vendor. messages and migrations are automatically created as needed. There is no need for components. In 2.0, you can expand classes into any directory. They will be loaded automatically if their namespace matches. If you don't feel comfortable without components, you can create one.
rmcreative.ru/blog/post/s-yii-1.1-na-yii-2.0--chas...