python etsm

Tiny state machine for python, see etsm

Description

Implement a bare bones state machine in many languages. This library aim to be simple as possible and support only basic features:

• states on object (owner)
• optional enter/exit methods
• virtual state user methods
• is in
• unrestricted transitions
• no runtime allocation

Install

include this file into your project etsm.py
or
import it

import etsm

Example

Simple

import etsm

class Foo:
    def __init__(self):
        self.__sm = etsm.StateMachine(self)
        self.__a = etsm.State(Foo.EnterA, Foo.ExitA)
        self.__b = etsm.State(Foo.EnterB, None)

    def EnterA(self):
        print(' ->A ', end='')

    def ExitA(self):
        print(' A-> ', end='')

    def EnterB(self):
        print(' ->B ', end='')

    # no exit for B
    # def ExitB(self):
    #     print(' B-> ', end='')

    def Run(self):
        self.__sm.Transition(self.__a);
        self.__sm.Transition(self.__b);
        self.__sm.Transition(None);

foo = Foo()
foo.Run()

Output : " ->A A-> ->B "
Sample: ab.py

Virtual State Methods

import etsm

class FooState(etsm.State):
    def __init__(self, enter, exit, tick):
        super().__init__(enter, exit)
        self.Tick = tick

class Foo:
    def __init__(self):
        self.__sm = etsm.StateMachine(self)
        self.__a = FooState(None, None, Foo.TickA)
        self.__b = FooState(None, None, Foo.TickB)

    def TickA(self):
        print(' A ', end='')

    def TickB(self):
        print(' B ', end='')

    # call tick on the current state, aka virtual call
    def Tick(self):
        if ( self.__sm.Current != None ):
            self.__sm.Current.Tick(self)

    def Run(self):
        self.Tick();
        self.__sm.Transition(self.__a);
        self.Tick();
        self.__sm.Transition(self.__b);
        self.Tick();
        self.__sm.Transition(None);
        self.Tick();

foo = Foo()
foo.Run()

Output: " A B "
Sample: virtual_call.py