Skip to content
A collection of design patterns/idioms in Python
Python Shell
Find file
Failed to load latest commit information.
.gitignore Remove __pycache__ and add __pycache__ to .gitignore Adjustment to UI and Business logic for injecting dependencies Small grammatical clarification add: basic unittest test Pep8 check for Update for understand the class Adapter added the state variable to borg and improved the README added the state variable to borg and improved the README Your code is too weak for PEP8. You lack DISCIPLINE Update Add alternative implementation of catalog for different levels of met… delete dead hyperlink prefer python3 over 2 Refactor MoveFileCommand Revert "edit the" Refactor decorator Your code is too weak for PEP8. You lack DISCIPLINE improved readability Updated flyweight with metaclass, made it more generic minor edit fix mistake usage of self param in recursive func and [] as default p… add __future__ print_function as print(number, end=' ') won't work in… Add pattern: lazy_evaluation Your code is too weak for PEP8. You lack DISCIPLINE deepcopy logic inverted In newly decoupled code: added a doc string to inner class Price Minor pep8 changes. Most salient is that membership test should be 'x… Your code is too weak for PEP8. You lack DISCIPLINE PEP8 changes fix typo Address PR comments Fix a small error in registry pattern. add output to the bottom of the and adaptation with … add __future__.print_function for better print add: unit test / delete: revert to initial version Add output to bottom of scripts add: test undo / change: cls name, setup, teardown add: docstring for strategy test file Your code is too weak for PEP8. You lack DISCIPLINE


A collection of design patterns and idioms in Python.

When an implementation is added or modified, be sure to update this file and rerun (eg. ./ to keep the output comments at the bottom up to date.

Current Patterns:

Creational Patterns:

Pattern Description
abstract_factory use a generic function with specific factories
borg a singleton with shared-state among instances
builder instead of using multiple constructors, builder object receives parameters and returns constructed objects
factory_method delegate a specialized function/method to create instances
lazy_evaluation lazily-evaluated property pattern in Python
pool preinstantiate and maintain a group of instances of the same type
prototype use a factory and clones of a prototype for new instances (if instantiation is expensive)

Structural Patterns:

Pattern Description
3-tier data<->business logic<->presentation separation (strict relationships)
adapter adapt one interface to another using a white-list
bridge a client-provider middleman to soften interface changes
composite encapsulate and provide access to a number of different objects
decorator wrap functionality with other functionality in order to affect outputs
facade use one class as an API to a number of others
flyweight transparently reuse existing instances of objects with similar/identical state
front_controller single handler requests coming to the application
mvc model<->view<->controller (non-strict relationships)
proxy an object funnels operations to something else

Behavioral Patterns:

Pattern Description
chain apply a chain of successive handlers to try and process the data
catalog general methods will call different specialized methods based on construction parameter
chaining_method continue callback next object method
command bundle a command and arguments to call later
mediator an object that knows how to connect other objects and act as a proxy
memento generate an opaque token that can be used to go back to a previous state
observer provide a callback for notification of events/changes to data
publish_subscribe a source syndicates events/data to 0+ registered listeners
registry keep track of all subclasses of a given class
specification business rules can be recombined by chaining the business rules together using boolean logic
state logic is organized into a discrete number of potential states and the next state that can be transitioned to
strategy selectable operations over the same data
template an object imposes a structure but takes pluggable components
visitor invoke a callback for all items of a collection


Pattern Description
graph_search (graphing algorithms, not design patterns)
Something went wrong with that request. Please try again.