/python-patterns

A collection of design patterns/idioms in Python

Primary LanguagePython

python-patterns

A collection of design patterns and idioms in Python.

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

Current Patterns:

Pattern Description
3-tier data<->business logic<->presentation separation (strict relationships)
abstract_factory use a generic function with specific factories
adapter adapt one interface to another using a whitelist
borg a singleton with shared-state among instances
bridge a client-provider middleman to soften interface changes
builder call many little discrete methods rather than having a huge number of constructor parameters
catalog general methods will call different specialized methods based on construction parameter
chain apply a chain of successive handlers to try and process the data
chaining_method continue callback next object method
command bundle a command and arguments to call later
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
factory_method delegate a specialized function/method to create instances
flyweight transparently reuse existing instances of objects with similar/identical state
graph_search (graphing algorithms, not design patterns)
lazy_evaluation lazily-evaluated property pattern in Python
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
mvc model<->view<->controller (non-strict relationships)
observer provide a callback for notification of events/changes to data
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)
proxy an object funnels operations to something else
publish_subscribe a source syndicates events/data to 0+ registered listeners
state logic is org'd 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