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 |
front_controller | single handler requests coming to the application |
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 |
registry | keeping 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 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 |