GenServer Callbacks: init

GenServer callbacks in-depth

The best way to learn about callbacks is to see them in action. We’ll add some functionality to the SendServer module and introduce the most common GenServer callbacks along the way.

We can implement a callback by declaring it in the SendServer module like any other function. By doing this, we are replacing the default function that GenServer provides. This is sometimes called overriding the default implementation. When we implement a callback, there are two things we need to know:

• What arguments does the callback function take?

• What return values are supported?

Callbacks covered

We are going to cover the following callback functions for the GenServer behaviour:

• handle_call/3

• handle_cast/2

• handle_continue/2

• handle_info/2

• init/1

• terminate/2 ...