design_patterns | Design pattern in Python | Architecture library

 by   onesuper Python Version: Current License: No License

kandi X-RAY | design_patterns Summary

kandi X-RAY | design_patterns Summary

design_patterns is a Python library typically used in Architecture applications. design_patterns has no bugs, it has no vulnerabilities and it has low support. However design_patterns build file is not available. You can download it from GitHub.

Several basic design patterns implemented with Python's OO features. All these examples came from an interesting book.
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              design_patterns has a low active ecosystem.
              It has 5 star(s) with 0 fork(s). There are no watchers for this library.
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              It had no major release in the last 6 months.
              design_patterns has no issues reported. There are no pull requests.
              It has a neutral sentiment in the developer community.
              The latest version of design_patterns is current.

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              design_patterns has no bugs reported.

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              design_patterns has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

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              design_patterns does not have a standard license declared.
              Check the repository for any license declaration and review the terms closely.
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              Without a license, all rights are reserved, and you cannot use the library in your applications.

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              design_patterns releases are not available. You will need to build from source code and install.
              design_patterns has no build file. You will be need to create the build yourself to build the component from source.

            Top functions reviewed by kandi - BETA

            kandi has reviewed design_patterns and discovered the below as its top functions. This is intended to give you an instant insight into design_patterns implemented functionality, and help decide if they suit your requirements.
            • creates a new operation
            • Initialize cash .
            • Print the application information .
            • Calculates the result .
            • Write the program .
            • Declare a member .
            • Method to perform Method A
            • Returns a website category .
            • Displays the node .
            • Loads the hypervisor .
            Get all kandi verified functions for this library.

            design_patterns Key Features

            No Key Features are available at this moment for design_patterns.

            design_patterns Examples and Code Snippets

            No Code Snippets are available at this moment for design_patterns.

            Community Discussions

            QUESTION

            Observer - specifying modifications of interest explicitly - JAVA implementation
            Asked 2020-Dec-10 at 16:55

            I asked here how I should handle the situation when I need to inform observers only when specific attribute of object changes.

            I received very nice reply with reference to GoF where is written:

            Blockquote Specifying modifications of interest explicitly. You can improve update efficiency by extending the subject's registration interface to allow registering observers only for specific events of interest. When such an event occurs, the subject informs only those observers that have registered interest in that event. One way to support this uses the notion of aspects for Subject objects. To register interest in particular events, observers are attached to their subjects using

            void Subject::Attach(Observer*, Aspects interest);

            Blockquote where interest specifies the event of interest. At notification time, the subject supplies the changed aspect to its observers as a parameter to the Update operation. For example:

            void Observer::Update(Subject*, Aspect& interest);

            This makes sense and I would like to ask how to correctly implement this in Java. I have few ideas but I am not sure if there isn't something better.

            Let's imagine I have subject class WeatherStation[temperature, humidity, windSpeed ...] and I have observer class LimitedDisplay[show (shows only temperature and humidity) and for some reason I need that the display should be able to differentiate when only temperature was changed and when only humidity was changed.

            I was thinking that I could create some enum WeatherStationInterest[TEMPERATURE, HUMIDITY WIND_SPEED...] and then have the subject interface like this:

            ...

            ANSWER

            Answered 2020-Dec-10 at 11:31

            Another option is to have a set of interfaces:

            Source https://stackoverflow.com/questions/65233285

            QUESTION

            Builder Pattern and LSP
            Asked 2020-Sep-10 at 00:01

            I was going through Builder pattern and had a couple of question that I thought needed clarification

            1. Is builder pattern implemented through Abstract class or through interfaces. There are few posts that uses interface https://sourcemaking.com/design_patterns/builder
              https://refactoring.guru/design-patterns/builder
              ...can list more
              and others uses abstract class https://www.dofactory.com/net/builder-design-pattern

            Note: The way I think is that it should be implemented using Abstract class. This rationale is based on the assumption that this way I may/may not implement them in derived class (as there could be a possibility that a few concrete class does not implement them)...
            This assumption could be entirely wrong though.

            1. If the above assumption is wrong then wont it violate LSP. Since one condition in LSP say that you cant have "not implemented methods" in your derived class.

            Or I have misunderstood it completely...

            ...

            ANSWER

            Answered 2020-Sep-10 at 00:01

            This became too long for a comment...

            The patterns from the GoF book are older than Java. It was Java that later introduced the (silly) distinction between interface and abstract class. When the GoF refers to an interface, they simply mean an abstraction, and you can implement it using any language feature that enables abstraction.

            That being said, the GoF Builder Pattern is overcomplicated. The pattern is useful even without polymorphism. And I think that is how it's most often implemented. If you're using Java, that would be Josh Bloch's Builder Pattern from Effective Java.

            I don't mean to dismiss the LSP question, but if the real goal here is to learn to use a Builder effectively, then my advice is to ignore the (outdated) version from the GoF and look at a modern implementation where that question doesn't arise. If you really wanted to ask about the LSP, then I suggest a new question focused specifically on that topic, separate from the Builder Pattern.

            To more directly address the questions in the OP,

            1. The builder pattern can be implemented through abstract classes or through interfaces. It does not matter which. Modern implementations more often use neither.
            2. LSP conformity will depend on how you implement (and document) the pattern. It would be possible to violate the LSP (or not) using interfaces or abstract classes. Eliminating both eliminates this question.

            Source https://stackoverflow.com/questions/63736569

            QUESTION

            Copy constructor on "Observer pattern"
            Asked 2019-Oct-03 at 16:29

            Suppose we a design pattern similar to this one:

            ...

            ANSWER

            Answered 2019-Oct-03 at 16:29

            A move constructor would be appropriate:

            Source https://stackoverflow.com/questions/58222961

            QUESTION

            Singleton test not working when var is instantiated with *
            Asked 2019-Jun-12 at 22:01

            I'm following the Singleton design pattern as described in this book (https://github.com/PacktPublishing/Go-Design-Patterns/blob/master/Chapter02/main.go) and I have this code in file "singleton2.go":

            ...

            ANSWER

            Answered 2019-Jun-12 at 22:01

            Follow the logic of your code and it's apparent where the problem is.

            When you declare, but do not initialize the singleton (var instance *singleton) then instance is nil. Calling GetInstance evaluates instance == nil as true and returns a new *singleton every time it is called. That is why counter2 will never equal expectedCounter - each call to GetInstance is returning a new counter instance.

            When you initialize the singleton instance (var instance = &singleton{}) then calls to GetInstance will return that singleton instance since it is not nil.

            I imagine you'd want to modify GetInstance to something like this:

            Source https://stackoverflow.com/questions/56534491

            QUESTION

            How to access a parent class attribute without breaking data encapsulation?
            Asked 2019-Jun-09 at 07:39

            In the 1994 book Design Patterns: Elements of Reusable Object-Oriented Software by the "Gang of Four", I noticed in the C++ code examples that all methods are either declared as public or protected (never as private) and that all attributes are declared as private (never as public or protected).

            In the first case, I suppose that the authors used protected methods instead of private methods to allow implementation inheritance (subclasses can delegate to them).

            In the second case, while I understand that avoiding public and protected attributes prevents breaking data encapsulation, how do you do without them if a subclass need access a parent class attribute?

            For example, the following Python code would have raised an AttributeError at the get_salary() method call if the _age attribute was private instead of protected, that is to say if it was named __age:

            ...

            ANSWER

            Answered 2019-Jun-09 at 07:39

            I have finally found out an obvious solution by myself: redeclaring the private attribute of the parent class in the subclass:

            Source https://stackoverflow.com/questions/56484622

            QUESTION

            How to protect function from base class in Python?
            Asked 2019-Apr-15 at 20:18

            I am currently learning the Template Method pattern in python.

            I am wondering if there is any way to protect some of the functions from the base class so that the subclass cannot overwrite? As below, the _primitive_operation_3 from the subclass overwrites the same function from the base class.

            ...

            ANSWER

            Answered 2019-Apr-15 at 18:38

            You can't prevent subclasses from using the same names, no. You can protect names against accidental shadowing, however, by giving the name a double underscore prefix:

            Source https://stackoverflow.com/questions/55695067

            QUESTION

            How to keep or properly cast object Type?
            Asked 2019-Jan-12 at 21:30

            Im dealing with this problem.

            I have base class Worker that is abstract. Its base class for Driver and AmountBonus. That Bonus is writed based on Decorator design pattern. My decorator decorate one of property from Worker.

            How it looks in code:

            ...

            ANSWER

            Answered 2019-Jan-10 at 19:09

            What you're doing makes no sense. Decorators are utility classes; they overlay programmatic functionality on to the classes they decorate. They are not something that can nor should be persisted to something like a database.

            In other words, if your object is a Driver, then you need to keep it a Driver, not wrap it in an AmountBonus decorator and then attempt to persist that. Later, if you need whatever functionality the AmountBonus decorator adds again, you simply wrap your Driver instance in it again.

            It doesn't even look like you're doing anything interesting with the decorator here, but if there is something that occurs just by the act of wrapping a Driver instance, then you'll need to fetch out somehow that wrapped Driver instance afterwards to actually save that and not your decorator.

            Source https://stackoverflow.com/questions/54134966

            QUESTION

            Decorator with abstraction, dont get decorated value properly
            Asked 2019-Jan-08 at 12:28

            Im trying to do Decorator Design Pattern and it is what i got:

            My base class is an abstract Worker class:

            ...

            ANSWER

            Answered 2019-Jan-08 at 12:28

            I have made some modifications to your code :

            Source https://stackoverflow.com/questions/54091031

            QUESTION

            Get reference to object from base class. Decorator design pattern
            Asked 2019-Jan-08 at 10:30

            Im dealing with Decorator design pattern. What i got now:

            My Base abstract class Worker:

            ...

            ANSWER

            Answered 2019-Jan-08 at 10:30

            By turning your private Worker worker { get; set; } into protected Worker worker { get; set; } classes outside cannot access it, but base classes can. This works even if the base class is abstract

            Edit: This would also be a good time to learn about C# naming conventions ;) MSDN docs
            Edit 2: As this comment points out, you probably want to use a private set with your Worker worker

            Edit after question Edit: You still (only if you want) need the Worker in the Bonus class but you do not need to declare private Worker worker; again, as this (correctly pointed out by intellisense) hides the Bonus.worker worker. If the Bonus.Worker is set to protected, and not private, you can use it from your inherited classes without having to declare it again. This would be the result:

            Source https://stackoverflow.com/questions/54089322

            QUESTION

            C# - Unit testing Factory Design Pattern
            Asked 2018-Oct-16 at 17:10

            I'm working on a project and I have to Unit Test a Factory Design pattern in C#. Currently im stuck and I have no idea what I have too do. Can someone help me out? I want to Unit Test this code:

            ...

            ANSWER

            Answered 2018-Oct-16 at 16:58

            Create an instance of the subject under test and provide the necessary dependencies.

            Source https://stackoverflow.com/questions/52839852

            Community Discussions, Code Snippets contain sources that include Stack Exchange Network

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            Install design_patterns

            You can download it from GitHub.
            You can use design_patterns like any standard Python library. You will need to make sure that you have a development environment consisting of a Python distribution including header files, a compiler, pip, and git installed. Make sure that your pip, setuptools, and wheel are up to date. When using pip it is generally recommended to install packages in a virtual environment to avoid changes to the system.

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