Skip to content

docs: add mermaid diagrams #469

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
faif merged 7 commits into from
Mar 13, 2026
Merged

docs: add mermaid diagrams #469

Changes from 1 commit
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
964f3f2
docs: add mermaid diagrams
maxkrivachev-web Mar 4, 2026
f393fbd
Update README.md
maxkrivachev-web Mar 6, 2026
cf4fd6d
docs: add mermaid diagrams
maxkrivachev-web Mar 9, 2026
d40a423
docs: add mermaid diagrams
maxkrivachev-web Mar 9, 2026
f311afd
docs: add mermaid diagrams
maxkrivachev-web Mar 9, 2026
ce1cef0
docs: add mermaid diagrams
maxkrivachev-web Mar 9, 2026
f44674f
docs: add mermaid diagrams
maxkrivachev-web Mar 9, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
docs: add mermaid diagrams
  • Loading branch information
@maxkrivachev-web
maxkrivachev-web authored Mar 9, 2026
commit f311afdfb2e01afd661519d65b402a61e8f61c91
121 changes: 88 additions & 33 deletions README.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@

A collection of design patterns and idioms in Python.

Remember that each pattern has its own trade-offs. And you need to pay attention more to why you're choosing a certain pattern than to how to implement it.

## Creational Patterns

> Patterns that deal with **object creation** — abstracting and controlling how instances are made.
Expand All @@ -20,14 +22,14 @@ graph LR
```

| Pattern | Description |
|:------- |:----------- |
| [abstract_factory](patterns/creational/abstract_factory.py) | use a generic interface to create a family of related objects |
|:-------:| ----------- |
| [abstract_factory](patterns/creational/abstract_factory.py) | use a generic function with specific factories |
| [borg](patterns/creational/borg.py) | a singleton with shared-state among instances |
| [builder](patterns/creational/builder.py) | instead of using complex constructors, isolate the construction of an object and make it multi-step |
| [factory](patterns/creational/factory.py) | delegate the creation of objects to specialized methods or classes |
| [lazy_evaluation](patterns/creational/lazy_evaluation.py) | wait until the value is needed to calculate it |
| [pool](patterns/creational/pool.py) | preinstantiate and maintain a group of objects of the same type |
| [prototype](patterns/creational/prototype.py) | use a factory to create new objects by copying an existing instance |
| [builder](patterns/creational/builder.py) | instead of using multiple constructors, builder object receives parameters and returns constructed objects |
| [factory](patterns/creational/factory.py) | delegate a specialized function/method to create instances |
| [lazy_evaluation](patterns/creational/lazy_evaluation.py) | lazily-evaluated property pattern in Python |
| [pool](patterns/creational/pool.py) | preinstantiate and maintain a group of instances of the same type |
| [prototype](patterns/creational/prototype.py) | use a factory and clones of a prototype for new instances (if instantiation is expensive) |
| [singleton](patterns/creational/singleton.py) | restrict the instantiation of a class to one object |

## Structural Patterns
Expand All @@ -53,17 +55,17 @@ graph TD
```

| Pattern | Description |
|:------- |:----------- |
|:-------:| ----------- |
| [3-tier](patterns/structural/3-tier.py) | data<->business logic<->presentation separation (strict relationships) |
| [adapter](patterns/structural/adapter.py) | adapt one interface to another using a white-box wrapper |
| [bridge](patterns/structural/bridge.py) | decouple an abstraction from its implementation |
| [composite](patterns/structural/composite.py) | encapsulate a group of objects into a single object |
| [decorator](patterns/structural/decorator.py) | wrap a class to add new functionality without changing its structure |
| [facade](patterns/structural/facade.py) | provide a simplified interface to a complex system |
| [flyweight](patterns/structural/flyweight.py) | use sharing to support a large number of objects efficiently |
| [front_controller](patterns/structural/front_controller.py) | a single entry point for all requests to an application |
| [proxy](patterns/structural/proxy.py) | an object representing another object |
| [mvc](patterns/structural/mvc.py) | separate data (model), user interface (view), and logic (controller) |
| [adapter](patterns/structural/adapter.py) | adapt one interface to another using a white-list |
| [bridge](patterns/structural/bridge.py) | a client-provider middleman to soften interface changes |
| [composite](patterns/structural/composite.py) | lets clients treat individual objects and compositions uniformly |
| [decorator](patterns/structural/decorator.py) | wrap functionality with other functionality in order to affect outputs |
| [facade](patterns/structural/facade.py) | use one class as an API to a number of others |
| [flyweight](patterns/structural/flyweight.py) | transparently reuse existing instances of objects with similar/identical state |
| [front_controller](patterns/structural/front_controller.py) | single handler requests coming to the application |
| [mvc](patterns/structural/mvc.py) | model<->view<->controller (non-strict relationships) |
| [proxy](patterns/structural/proxy.py) | an object funnels operations to something else |

## Behavioral Patterns

Expand All @@ -86,20 +88,73 @@ graph LR
```

| Pattern | Description |
|:------- |:----------- |
| [chain_of_responsibility](patterns/behavioral/chain_of_responsibility.py) | allow multiple objects to handle a request without them needing to know about each other |
| [command](patterns/behavioral/command.py) | encapsulate a request as an object, allowing for parameterization and queuing |
| [catalog](patterns/behavioral/catalog.py) | a class that allows looking up other classes based on various criteria |
| [chaining_method](patterns/behavioral/chaining_method.py) | allow calling multiple methods on the same object in a single statement |
|:-------:| ----------- |
| [chain_of_responsibility](patterns/behavioral/chain_of_responsibility.py) | apply a chain of successive handlers to try and process the data |
| [catalog](patterns/behavioral/catalog.py) | general methods will call different specialized methods based on construction parameter |
| [chaining_method](patterns/behavioral/chaining_method.py) | continue callback next object method |
| [command](patterns/behavioral/command.py) | bundle a command and arguments to call later |
| [interpreter](patterns/behavioral/interpreter.py) | define a grammar for a language and use it to interpret statements |
| [iterator](patterns/behavioral/iterator.py) | provide a way to access elements of a collection sequentially |
| [mediator](patterns/behavioral/mediator.py) | encapsulate how a set of objects interact |
| [memento](patterns/behavioral/memento.py) | capture and restore an object's internal state |
| [observer](patterns/behavioral/observer.py) | allow objects to notify other objects about changes in their state |
| [publish_subscribe](patterns/behavioral/publish_subscribe.py) | allow objects to subscribe to events and receive notifications when they occur |
| [registry](patterns/behavioral/registry.py) | keep track of all instances of a class |
| [specification](patterns/behavioral/specification.py) | define a set of criteria that an object must meet |
| [state](patterns/behavioral/state.py) | allow an object to change its behavior when its internal state changes |
| [strategy](patterns/behavioral/strategy.py) | define a family of algorithms and make them interchangeable |
| [template](patterns/behavioral/template.py) | define the skeleton of an algorithm in a method, allowing subclasses to override specific steps |
| [visitor](patterns/behavioral/visitor.py) | separate an algorithm from the object structure it operates on |
| [iterator](patterns/behavioral/iterator.py) | traverse a container and access the container's elements |
| [iterator](patterns/behavioral/iterator_alt.py) (alt. impl.)| traverse a container and access the container's elements |
| [mediator](patterns/behavioral/mediator.py) | an object that knows how to connect other objects and act as a proxy |
| [memento](patterns/behavioral/memento.py) | generate an opaque token that can be used to go back to a previous state |
| [observer](patterns/behavioral/observer.py) | provide a callback for notification of events/changes to data |
| [publish_subscribe](patterns/behavioral/publish_subscribe.py) | a source syndicates events/data to 0+ registered listeners |
| [registry](patterns/behavioral/registry.py) | keep track of all subclasses of a given class |
| [servant](patterns/behavioral/servant.py) | provide common functionality to a group of classes without using inheritance |
| [specification](patterns/behavioral/specification.py) | business rules can be recombined by chaining the business rules together using boolean logic |
| [state](patterns/behavioral/state.py) | logic is organized into a discrete number of potential states and the next state that can be transitioned to |
| [strategy](patterns/behavioral/strategy.py) | selectable operations over the same data |
| [template](patterns/behavioral/template.py) | an object imposes a structure but takes pluggable components |
| [visitor](patterns/behavioral/visitor.py) | invoke a callback for all items of a collection |

## Design for Testability Patterns

| Pattern | Description |
|:-------:| ----------- |
| [dependency_injection](patterns/dependency_injection.py) | 3 variants of dependency injection |

## Fundamental Patterns

| Pattern | Description |
|:-------:| ----------- |
| [delegation_pattern](patterns/fundamental/delegation_pattern.py) | an object handles a request by delegating to a second object (the delegate) |

## Others

| Pattern | Description |
|:-------:| ----------- |
| [blackboard](patterns/other/blackboard.py) | architectural model, assemble different sub-system knowledge to build a solution, AI approach - non gang of four pattern |
| [graph_search](patterns/other/graph_search.py) | graphing algorithms - non gang of four pattern |
| [hsm](patterns/other/hsm/hsm.py) | hierarchical state machine - non gang of four pattern |

## Videos

* [Design Patterns in Python by Peter Ullrich](https://www.youtube.com/watch?v=bsyjSW46TDg)
* [Sebastian Buczyński - Why you don't need design patterns in Python?](https://www.youtube.com/watch?v=G5OeYHCJuv0)
* [You Don't Need That!](https://www.youtube.com/watch?v=imW-trt0i9I)
* [Pluggable Libs Through Design Patterns](https://www.youtube.com/watch?v=PfgEU3W0kyU)

## Contributing

When an implementation is added or modified, please review the following guidelines:

##### Docstrings
Add module level description in form of a docstring with links to corresponding references or other useful information.
Add "Examples in Python ecosystem" section if you know some. It shows how patterns could be applied to real-world problems.
[facade.py](patterns/structural/facade.py) has a good example of detailed description, but sometimes the shorter one as in [template.py](patterns/behavioral/template.py) would suffice.

##### Python 2 compatibility
To see Python 2 compatible versions of some patterns please check-out the [legacy](https://github.com/faif/python-patterns/tree/legacy) tag.

##### Update README
When everything else is done - update corresponding part of README.

##### Travis CI
Please run the following before submitting a patch:
- `black .` This lints your code.
- Either `tox` or `tox -e ci37` for unit tests.
- If you have a bash compatible shell, use `./lint.sh`.

## Contributing via issue triage [![Open Source Helpers](https://www.codetriage.com/faif/python-patterns/badges/users.svg)](https://www.codetriage.com/faif/python-patterns)
You can triage issues and pull requests on [CodeTriage](https://www.codetriage.com/faif/python-patterns).