https://github.com/pavlos/gen_fsm

Elixir wrapper around OTP's gen_fsm
https://github.com/pavlos/gen_fsm

Last synced: 7 days ago
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Elixir wrapper around OTP's gen_fsm

• Host: GitHub
• URL: https://github.com/pavlos/gen_fsm
• Owner: pavlos
• License: other
• Created: 2016-04-01T08:01:23.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2020-03-03T22:27:24.000Z (over 4 years ago)
• Last Synced: 2024-10-23T15:15:54.589Z (16 days ago)
• Language: Elixir
• Size: 21.5 KB
• Stars: 40
• Watchers: 2
• Forks: 3
• Open Issues: 5
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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• freaking_awesome_elixir - Elixir - A generic finite state-machine - Elixir wrapper around OTP's gen_fsm. (Algorithms and Data structures)
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README

        


# GenFSM

Elixir wrapper around Erlang's OTP gen_fsm.

## Motivation

Elixir [deprecated](https://github.com/elixir-lang/elixir/commit/455eb4c4ace81ce60b347558f9419fe3c33d8bf7)

its wrapper around OTP's gen_fsm from the standard library because it is difficult to understand and suggested that

developers seek other finite state machine implementations.

This is understandable, but some of us still need/prefer to use the OTP gen_fsm.

I took the basis of Elixir's old

[GenFSM.Behaviour](https://github.com/elixir-lang/elixir/blob/a6f048b3de4a971c15fc8b66397cf2e4597793cb/lib/elixir/lib/gen_fsm/behaviour.ex)

and added some additional convenience methods.  Currently missing are the `enter_loop` methods.

## Usage

The following example implement a simple state machine with two states, `martin` and `paul`. The state machine will initialize into the `martin` state, when the state machine receive `:hello` as the input it will transition between the states, from `martin` to `paul` and `"Hello, Paul"` will get printed to the console.

```elixir

defmodule Conversation do

  use GenFSM

  def start_link() do

    GenFSM.start_link(__MODULE__, :na)

  end

  def hello(pid) do

    GenFSM.send_event(pid, :hello)

  end

  def init(:na), do: {:ok, :martin, nil}

  def martin(:hello, nil) do

    IO.puts "Hello, Paul"

    {:next_state, :paul, nil}

  end

  def paul(:hello, nil) do

    IO.puts "Hello, Martin"

    {:next_state, :martin, nil}

  end

end

```

A conversation could go like this:

``` elixir

iex(2)> {:ok, pid} = Conversation.start_link

{:ok, #PID<0.165.0>}

iex(3)> Conversation.hello pid

Hello, Paul

:ok

iex(4)> Conversation.hello pid

Hello, Martin

:ok

iex(5)>

```

## Installation

If [available in Hex](https://hex.pm/docs/publish), the package can be installed as:

  1. Add gen_fsm to your list of dependencies in `mix.exs`:

        def deps do

          [{:gen_fsm, "~> 0.1.0"}]

        end

## Documentation

Complete [API documentation](http://erlang.org/doc/man/gen_fsm.html) can be found at

http://erlang.org/doc/man/gen_fsm.html

and OTP [design principal documentation](http://erlang.org/doc/design_principles/fsm.html)

lives at http://erlang.org/doc/man/gen_fsm.html