# <a name="transitions-module"></a> transitions
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[](https://pypi.org/project/transitions)
[](https://copr.fedorainfracloud.org/coprs/aleneum/python-transitions/)
[](https://github.com/pytransitions/transitions/compare/0.9.2...master)
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A lightweight, object-oriented state machine implementation in Python with many extensions. Compatible with Python 2.7+ and 3.0+.
## Installation
pip install transitions
... or clone the repo from GitHub and then:
python setup.py install
## Table of Contents
- [Quickstart](#quickstart)
- [Non-Quickstart](#the-non-quickstart)
- [Some key concepts](#some-key-concepts)
- [Basic initialization](#basic-initialization)
- [States](#states)
- [Callbacks](#state-callbacks)
- [Checking state](#checking-state)
- [Enumerations](#enum-state)
- [Transitions](#transitions)
- [Triggering a transition](#triggers)
- [Automatic transitions](#automatic-transitions-for-all-states)
- [Transitioning from multiple states](#transitioning-from-multiple-states)
- [Reflexive transitions from multiple states](#reflexive-from-multiple-states)
- [Internal transitions](#internal-transitions)
- [Ordered transitions](#ordered-transitions)
- [Queued transitions](#queued-transitions)
- [Conditional transitions](#conditional-transitions)
- [Check transitions](#check-transitions)
- [Callbacks](#transition-callbacks)
- [Callable resolution](#resolution)
- [Callback execution order](#execution-order)
- [Passing data](#passing-data)
- [Alternative initialization patterns](#alternative-initialization-patterns)
- [Logging](#logging)
- [(Re-)Storing machine instances](#restoring)
- [Typing support](#typing-support)
- [Extensions](#extensions)
- [Hierarchical State Machine](#hsm)
- [Diagrams](#diagrams)
- [Threading](#threading)
- [Async](#async)
- [State features](#state-features)
- [Django](#django-support)
- [Bug reports etc.](#bug-reports)
## Quickstart
They say [a good example is worth](https://www.google.com/webhp?ie=UTF-8#q=%22a+good+example+is+worth%22&start=20) 100 pages of API documentation, a million directives, or a thousand words.
Well, "they" probably lie... but here's an example anyway:
```python
from transitions import Machine
import random
class NarcolepticSuperhero(object):
# Define some states. Most of the time, narcoleptic superheroes are just like
# everyone else. Except for...
states = ['asleep', 'hanging out', 'hungry', 'sweaty', 'saving the world']
def __init__(self, name):
# No anonymous superheroes on my watch! Every narcoleptic superhero gets
# a name. Any name at all. SleepyMan. SlumberGirl. You get the idea.
self.name = name
# What have we accomplished today?
self.kittens_rescued = 0
# Initialize the state machine
self.machine = Machine(model=self, states=NarcolepticSuperhero.states, initial='asleep')
# Add some transitions. We could also define these using a static list of
# dictionaries, as we did with states above, and then pass the list to
# the Machine initializer as the transitions= argument.
# At some point, every superhero must rise and shine.
self.machine.add_transition(trigger='wake_up', source='asleep', dest='hanging out')
# Superheroes need to keep in shape.
self.machine.add_transition('work_out', 'hanging out', 'hungry')
# Those calories won't replenish themselves!
self.machine.add_transition('eat', 'hungry', 'hanging out')
# Superheroes are always on call. ALWAYS. But they're not always
# dressed in work-appropriate clothing.
self.machine.add_transition('distress_call', '*', 'saving the world',
before='change_into_super_secret_costume')
# When they get off work, they're all sweaty and disgusting. But before
# they do anything else, they have to meticulously log their latest
# escapades. Because the legal department says so.
self.machine.add_transition('complete_mission', 'saving the world', 'sweaty',
after='update_journal')
# Sweat is a disorder that can be remedied with water.
# Unless you've had a particularly long day, in which case... bed time!
self.machine.add_transition('clean_up', 'sweaty', 'asleep', conditions=['is_exhausted'])
self.machine.add_transition('clean_up', 'sweaty', 'hanging out')
# Our NarcolepticSuperhero can fall asleep at pretty much any time.
self.machine.add_transition('nap', '*', 'asleep')
def update_journal(self):
""" Dear Diary, today I saved Mr. Whiskers. Again. """
self.kittens_rescued += 1
@property
def is_exhausted(self):
""" Basically a coin toss. """
return random.random() < 0.5
def change_into_super_secret_costume(self):
print("Beauty, eh?")
```
There, now you've baked a state machine into `NarcolepticSuperhero`. Let's take him/her/it out for a spin...
```python
>>> batman = NarcolepticSuperhero("Batman")
>>> batman.state
'asleep'
>>> batman.wake_up()
>>> batman.state
'hanging out'
>>> batman.nap()
>>> batman.state
'asleep'
>>> batman.clean_up()
MachineError: "Can't trigger event clean_up from state asleep!"
>>> batman.wake_up()
>>> batman.work_out()
>>> batman.state
'hungry'
# Batman still hasn't done anything useful...
>>> batman.kittens_rescued
0
# We now take you live to the scene of a horrific kitten entreement...
>>> batman.distress_call()
'Beauty, eh?'
>>> batman.state
'saving the world'
# Back to the crib.
>>> batman.complete_mission()
>>> batman.state
'sweaty'
>>> batman.clean_up()
>>> batman.state
'asleep' # Too tired to shower!
# Another productive day, Alfred.
>>> batman.kittens_rescued
1
```
While we cannot read the mind of the actual batman, we surely can visualize the current state of our `NarcolepticSuperhero`.
Have a look at the [Diagrams](#diagrams) extensions if you want to know how.
## The non-quickstart
A state machine is a _model_ of behavior composed of a finite number of _states_ and _transitions_ between those states. Within each state and transition some _action_ can be performed. A state machine needs to start at some _initial state_. When using `transitions`, a state machine may consist of multiple objects where some (_machines_) contain definitions for the manipulation of other (_models_). Below, we will look at some core concepts and how to work with them
transitions-Python轻量级、面向对象的有限状态机实现.zip （82个子文件） 
transitions-master 
Changelog.md 32KB noxfile.py 937B setup.py 2KB .coveragerc 49B .github ISSUE_TEMPLATE support-request.md 1KB feature_request.md 615B bug_report.md 629B workflows pytest.yml 2KB pytest.ini 125B LICENSE 1KB tests utils.py 3KB __init__.py 0B test_imports.py 642B test_codestyle.py 2KB test_factory.py 2KB test_mermaid.py 10KB test_core.py 51KB test_async.py 29KB test_reuse.py 22KB test_add_remove.py 3KB test_parallel.py 11KB test_markup.py 8KB test_enum.py 14KB test_pygraphviz.py 4KB test_states.py 8KB test_threading.py 11KB test_graphviz.py 22KB test_nesting.py 41KB test_experimental.py 8KB examples Frequently asked questions.ipynb 39KB Playground.ipynb 9KB Graph MIxin Demo.ipynb 741KB Graph MIxin Demo Nested.ipynb 583KB mypy.ini 378B
requirements.txt 4B MANIFEST.in 347B .gitignore 221B setup.cfg 134B binder apt.txt 9B postBuild 35B requirements.txt 13B requirements_mypy.txt 24B appveyor.yml 1KB .pylintrc 15KB README.md 97KB transitions __init__.py 554B version.py 174B experimental utils.py 5KB __init__.py 0B utils.pyi 2KB version.pyi 17B core.pyi 11KB __init__.pyi 264B py.typed 1B core.py 60KB extensions diagrams_pygraphviz.py 10KB asyncio.py 33KB __init__.py 836B locking.py 8KB diagrams_base.pyi 2KB diagrams_graphviz.py 12KB diagrams_graphviz.pyi 3KB states.py 10KB markup.pyi 4KB nesting.py 60KB __init__.pyi 689B asyncio.pyi 9KB diagrams.py 12KB states.pyi 1KB locking.pyi 3KB factory.pyi 2KB diagrams_mermaid.pyi 2KB nesting.pyi 10KB factory.py 4KB diagrams_mermaid.py 11KB diagrams.pyi 4KB markup.py 12KB diagrams_pygraphviz.pyi 2KB diagrams_base.py 6KB conftest.py 615B requirements_test.txt 67B requirements_diagrams.txt 20B资源评论
