python state machine

A finite state machine (FSM) represents a computational model characterized by states, transitions, inputs, and outputs. The machine occupies a singular state at any given moment and can transition to other states. A transition is what alters the machine’s current state.

Finite state machines offer solutions to a plethora of problems. In our daily lives, we encounter FSMs in vending machines, elevators, and traffic lights. More complex applications include artificial intelligence, parsing languages, and designing communication protocols.

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Finite State Machine Example

To get started with building a Finite State Machine in Python, you first need to install the Fysom module:

sudo pip install fysom

Following the installation, let’s create a FSM with two potential states: ‘sleeping’ and ‘awake’. The transitions between these states will be the methods wakeup() and sleep().

Here’s an illustrative example in Python:

from fysom import *

fsm = Fysom({
    'initial': 'awake',
    'final': 'red',
    'events': [
        {'name': 'wakeup', 'src': 'sleeping', 'dst': 'awake'},
        {'name': 'sleep',  'src': 'awake',   'dst': 'sleeping'}
    ]
})

print(fsm.current)   # Output: awake
fsm.sleep()
print(fsm.current)   # Output: sleeping
fsm.wakeup()
print(fsm.current)   # Output: awake

The output of the above code will be:

awake
sleeping
awake

Finite State Machines in Python

For those interested in diving deeper, there are several Python libraries dedicated to implementing Finite State Machines. A couple of noteworthy mentions include:

• Fysom
• Fsme