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A Collection of Design Patterns/Idioms in Python
Python Patterns
A collection of design patterns and idioms in Python.
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 | 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 | lets clients treat individual objects and compositions uniformly |
| 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_of_responsibility | 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 |
| iterator | traverse a container and access the container's elements |
| iterator (alt. impl.) | traverse a container and access the container's elements |
| 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 |
Design for Testability Patterns:
| Pattern | Description |
|---|---|
| dependency_injection | 3 variants of dependency injection |
Fundamental Patterns:
| Pattern | Description |
|---|---|
| delegation_pattern | an object handles a request by delegating to a second object (the delegate) |
Others:
| Pattern | Description |
|---|---|
| blackboard | architectural model, assemble different sub-system knowledge to build a solution, AI approach - non gang of four pattern |
| graph_search | graphing algorithms - non gang of four pattern |
| hsm | hierarchical state machine - non gang of four pattern |
Videos
Design Patterns in Python by Peter Ullrich
Sebastian Buczyński - Why you don't need design patterns in Python?
Pluggable Libs Through Design Patterns
Contributing
When an implementation is added or modified, please review the following guidelines:
Output
All files with example patterns have ### OUTPUT ### section at the bottom (migration to OUTPUT = """...""" is in progress).
Run append_output.sh (e.g. ./append_output.sh borg.py) to generate/update it.
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 has a good example of detailed description, but sometimes the shorter one as in template.py would suffice.
In some cases class-level docstring with doctest would also help (see adapter.py) but readable OUTPUT section is much better.
Python 2 compatibility
To see Python 2 compatible versions of some patterns please check-out the legacy tag.
Update README
When everything else is done - update corresponding part of README.
Travis CI
Please run tox or tox -e ci37 before submitting a patch to be sure your changes will pass CI.
You can also run flake8 or pytest commands manually. Examples can be found in tox.ini.
Contributing via issue triage
You can triage issues and pull requests which may include reproducing bug reports or asking for vital information, such as version numbers or reproduction instructions. If you would like to start triaging issues, one easy way to get started is to subscribe to python-patterns on CodeTriage.
Download Details:
Author: faif
Source Code: https://github.com/faif/python-patterns
#python #designpatterns
What is GEEK
Buddha Community
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top 30 Python Tips and Tricks for Beginners
Welcome to my Blog , In this article, you are going to learn the top 10 python tips and tricks.
1) swap two numbers.
2) Reversing a string in Python.
3) Create a single string from all the elements in list.
4) Chaining Of Comparison Operators.
5) Print The File Path Of Imported Modules.
6) Return Multiple Values From Functions.
7) Find The Most Frequent Value In A List.
8) Check The Memory Usage Of An Object.
…
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Lambda, Map, Filter functions in python
Welcome to my Blog, In this article, we will learn python lambda function, Map function, and filter function.
Lambda function in python: Lambda is a one line anonymous function and lambda takes any number of arguments but can only have one expression and python lambda syntax is
Syntax: x = lambda arguments : expression
Now i will show you some python lambda function examples:
#python #anonymous function python #filter function in python #lambda #lambda python 3 #map python #python filter #python filter lambda #python lambda #python lambda examples #python map
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Why use Python for Software Development
No programming language is pretty much as diverse as Python. It enables building cutting edge applications effortlessly. Developers are as yet investigating the full capability of end-to-end Python development services in various areas.
By areas, we mean FinTech, HealthTech, InsureTech, Cybersecurity, and that's just the beginning. These are New Economy areas, and Python has the ability to serve every one of them. The vast majority of them require massive computational abilities. Python's code is dynamic and powerful - equipped for taking care of the heavy traffic and substantial algorithmic capacities.
Programming advancement is multidimensional today. Endeavor programming requires an intelligent application with AI and ML capacities. Shopper based applications require information examination to convey a superior client experience. Netflix, Trello, and Amazon are genuine instances of such applications. Python assists with building them effortlessly.
5 Reasons to Utilize Python for Programming Web Apps
Python can do such numerous things that developers can't discover enough reasons to admire it. Python application development isn't restricted to web and enterprise applications. It is exceptionally adaptable and superb for a wide range of uses.
Robust frameworks
Python is known for its tools and frameworks. There's a structure for everything. Django is helpful for building web applications, venture applications, logical applications, and mathematical processing. Flask is another web improvement framework with no conditions.
Web2Py, CherryPy, and Falcon offer incredible capabilities to customize Python development services. A large portion of them are open-source frameworks that allow quick turn of events.
Simple to read and compose
Python has an improved sentence structure - one that is like the English language. New engineers for Python can undoubtedly understand where they stand in the development process. The simplicity of composing allows quick application building.
The motivation behind building Python, as said by its maker Guido Van Rossum, was to empower even beginner engineers to comprehend the programming language. The simple coding likewise permits developers to roll out speedy improvements without getting confused by pointless subtleties.
Utilized by the best
Alright - Python isn't simply one more programming language. It should have something, which is the reason the business giants use it. Furthermore, that too for different purposes. Developers at Google use Python to assemble framework organization systems, parallel information pusher, code audit, testing and QA, and substantially more. Netflix utilizes Python web development services for its recommendation algorithm and media player.
Massive community support
Python has a steadily developing community that offers enormous help. From amateurs to specialists, there's everybody. There are a lot of instructional exercises, documentation, and guides accessible for Python web development solutions.
Today, numerous universities start with Python, adding to the quantity of individuals in the community. Frequently, Python designers team up on various tasks and help each other with algorithmic, utilitarian, and application critical thinking.
Progressive applications
Python is the greatest supporter of data science, Machine Learning, and Artificial Intelligence at any enterprise software development company. Its utilization cases in cutting edge applications are the most compelling motivation for its prosperity. Python is the second most well known tool after R for data analytics.
The simplicity of getting sorted out, overseeing, and visualizing information through unique libraries makes it ideal for data based applications. TensorFlow for neural networks and OpenCV for computer vision are two of Python's most well known use cases for Machine learning applications.
Summary
Thinking about the advances in programming and innovation, Python is a YES for an assorted scope of utilizations. Game development, web application development services, GUI advancement, ML and AI improvement, Enterprise and customer applications - every one of them uses Python to its full potential.
The disadvantages of Python web improvement arrangements are regularly disregarded by developers and organizations because of the advantages it gives. They focus on quality over speed and performance over blunders. That is the reason it's a good idea to utilize Python for building the applications of the future.
#python development services #python development company #python app development #python development #python in web development #python software development
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Builder Design Pattern
What is Builder Design Pattern ? Why we should care about it ?
Starting from **Creational Design Pattern, **so wikipedia says “creational design pattern are design pattern that deals with object creation mechanism, trying to create objects in manner that is suitable to the situation”.
The basic form of object creations could result in design problems and result in complex design problems, so to overcome this problem Creational Design Pattern somehow allows you to create the object.
Builder is one of the** Creational Design Pattern**.
When to consider the Builder Design Pattern ?
Builder is useful when you need to do lot of things to build an Object. Let’s imagine DOM (Document Object Model), so if we need to create the DOM, We could have to do lot of things, appending plenty of nodes and attaching attributes to them. We could also imagine about the huge XML Object creation where we will have to do lot of work to create the Object. A Factory is used basically when we could create the entire object in one shot.
As **Joshua Bloch (**He led the Design of the many library Java Collections Framework and many more) – “Builder Pattern is good choice when designing the class whose constructor or static factories would have more than handful of parameters”
#java #builder #builder pattern #creational design pattern #design pattern #factory pattern #java design pattern
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Python Tricks Every Developer Should Know
Python is awesome, it’s one of the easiest languages with simple and intuitive syntax but wait, have you ever thought that there might ways to write your python code simpler?
In this tutorial, you’re going to learn a variety of Python tricks that you can use to write your Python code in a more readable and efficient way like a pro.
Let’s get started
Swapping value in Python
Instead of creating a temporary variable to hold the value of the one while swapping, you can do this instead
>>> FirstName = "kalebu"
>>> LastName = "Jordan"
>>> FirstName, LastName = LastName, FirstName
>>> print(FirstName, LastName)
('Jordan', 'kalebu')
#python #python-programming #python3 #python-tutorials #learn-python #python-tips #python-skills #python-development