A design pattern is a general reusable solution to a commonly occurring problem in software design.

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What are the limitations of Factory design patterns? How to overcome?

As we know there are many ways, by which we can break a singleton implementation in Java. Similarly do we have any ways by which we can break factory method implementation in Java? if yes then how to ...
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57 views

A modification of singleton pattern

"Singleton" is widely considered anti-pattern ("bad" in everyday language). What about this alternative modified singleton pattern? An object constructor for our class ensures that at any given ...
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59 views

Static factory method in base class

An increasingly popular definition of factory method is: a static method of a class that returns an object of that class' type. But unlike a constructor, the actual object it returns might be an ...
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What's an optimal procedure to create a connected cyclic grid of nodes and edges for A* pathfinding

like the title says, I'm trying to create a grid of nodes that hold edges or connections to each other so I can perform A* algorithm to have objects traverse across them as seen in your standard RTS. ...
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Design pattern for application development [duplicate]

I have a Window class, which represents a window (there is only one instance of it), and has an instance of every object inside it. For example: class Window { public: //... private: Button ...
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2answers
51 views

Return values for a delete function in php

I am writing a wrapper function for database calls, and I am confused about the best way to handle the error cases. The function has only one argument, the id of the object to be deleted. I've ...
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How to design property files

I always wonder what is the best way to design your property files. I have few questions that I didn't find an answer to them Do we place all our labels / error messages in one file? Do we split the ...
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Business rules design pattern?

I'm working on an interface for implementing business rules in order to improve SOLID-ity; so I can move a lot of logic out of Web API controllers and into a business library. The Common Problem being ...
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23 views

The best implementation for fromJson factory method and json-mappings with inheritance?

I have BaseComponent (with field "type") and it's subclasses TextComponent, ListComponent, etc. Some of them has same fields. I want to create them and init their fields from json. Some of possible ...
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40 views

Where should view-specific data/logic be defined in a PHP MVC application?

After many hours of research and thinking I have found an understanding, then coming to question it again, I am struggling to find something concrete which I can grasp and apply to my code in a ...
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4answers
213 views

Is it too verbose to always have 'modified' time stamps on all entities within a database?

The question can be summarized as: In a database (regardless of type), would it be considered a good practice to always include updated, created (and possibly deleted) properties, for all entities,...
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Can a single Factory be used to create similar in purpose, but different in focus objects?

I am concerned about whether or not I am using FactoryMethod correctly. Background: I am refactoring legacy code and I have identified a pattern: there is a God Object that is created in memory,...
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84 views

How to remove circular reference when there is inter-dependence

I made an extensive research in previousv related questions, but since my questions is somewhat peculiar, I decided to create this new one. I am implementing a visualisation application (in JS). ...
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258 views

According to Demeter's law, is a class allowed to return one of its members?

I have three questions concerning Demeter's law. Apart from classes which were specifically appointed to return objects - such as factory and builder classes - is it okay for a method to return an ...
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Abilities interacting with aspects of other abilities - how to implement efficiently

In my game I want characters to be able to cast spells which deal a certain amount of damage of a certain type to other characters in the game. I also want abilities that negate an amount of damage ...
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1answer
50 views

UML: do I use aggregation or composition in this case?

I would like to draw a UML sketch to communicate part of a software but the type of relationship between classes does not seem very clear cut to me. Let's say I want to periodically fetch the recent ...
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1answer
69 views

How to decouple backend app?

I have heard this term many times, and it makes sense in theory. That app is doing many things and it'd be easier to manage, scale, test and improve them if they are not completely connected to each ...
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2answers
114 views

Ubiquitous language and resource based REST API?

I have posted a question regarding Ubiquitous language and maturity level in REST API. Ubiquitous language and maturity level in REST API? After some extensive coding I realized that further ...
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1answer
42 views

How to check foreign key dependency in ddd aggregate root

When I want to call a constructor on aggregate root class Task, I am interested how can I check if a passed taskType exists in TaskType repository (enforced later in DB on ORM level). I want to ...
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1answer
63 views

MVC: Display requsted content via the View

I'm trying to learn how the MVC pattern works so have been playing around a bit. I just wrote this, which was making sense to me, until I wanted to display the array content which has been collect by ...
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Should I create a settings provider implementing an interface for each handler?

Let's say I got a series of services that are handled by a central hub, part of the behavior of the application is controlled by a series of settings that are stored on a file. Right now when I get a ...
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Stateless vs Stateful ViewModel

Here are two links which briefly describe the difference between the two: stateless, stateful In short in the "Stateless" scenario we bind views directly to models, view models just expose the whole ...
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Is it a code smell to store generic objects in a container and then get object and downcast the objects from container?

For example, I have a game, which has some tools to increase the ability of the Player: Tool.h class Tool{ public: std::string name; }; And some tools: Sword.h class Sword : public Tool{ ...
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Why do I want this class to extend an interface, and what is the right design pattern for this?

Suppose I have an interface Employee and there are many classes that implement it, such as Bob, Joe, and Mary, none of which may be changed. public interface Employee{ public void work() } public ...
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How can you enforce a “do you really want to do this” confirmation in a publically exposed API?

Is there a commonly (or rarely) used pattern for a "confirming you want to do this" message when calling a function from a library? I have a API that exposes some operations that are potentially ...
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Should repository have a method for every specific database operation?

When following the standard service and repository patterns, should your repository contain a specific method for every database operation or should you just use the general methods, e.g. update? Take ...
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How do I write an API that makes use of many smaller APIs?

I have a solid set of classes that do the following build tables from data and templates advanced form serialization build forms from data and templates launch overlays with forms/wizards short poll ...
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75 views

Polymorphic constants in Java

I am designing some polymorphic code to perform mathematical operations. The idea is to abstract out the underlying representation of the data, as different use cases require different representations....
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Is it anti-pattern to alter domain model on front end?

We are making a quiz application, I'm trying to integrate my Angular 2 UI with the REST api. Our Quiz domain model consist of the following (simplified) hierarchy: -Quiz -Category -Question -Choice ...
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Generic request processing

I got a webservice that accepts multiple calls that require different handling and validation, using generics I've managed to create a common class that accepts a handler and a validator and it looks ...
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1answer
56 views

Complex Math Formula: Predict the value of variable if result is known

I have a very complex math formula/equation which involves exponential. Formula: X + 2 = Y *PS: The above is just an example to illustrate my problem. The real formula is way more complex than this....
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Could this be called a decorator pattern?

I want to add some extra methods closely related to Book without extending Book. So I found the decorator pattern. Most examples I have seen are eg. extending an abstract decorator class which ...
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432 views

Should a DAO be singleton or not?

I am developing a RESTful API and I think it is convenient to use DAOs for my resources because although I plan on just using memory to store them, I don't want to close a door to whoever is using my ...
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1answer
74 views

What design pattern(.Net) to use for multiple control design with multiple properties?

I have to design for a bunch of user control types, each of which share some common properties but some of which have special unique properties. For example, the common properties across all the ...
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Designing a flexible API with support for Callbacks

I am writing a Java library that needs to make http GET && POST requests. There will be two types of users of this library: Those with understanding of callbacks and know how to use them. ...
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Design pattern for managing three different objects

I´m looking for the best way to solve following problem: I have three lists of different objects: AppleJuice, OrangeJuice & Juice. All Juice properties exists in AppleJuice & OrangeJuice ...
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70 views

Best pattern to track actions inside a presenter

I have a MVP implementation, inside my presenter i have a lot of public methods like onSendMessage() for example. I need to track some of that methods, meaning track just call a trackClient....
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61 views

Knowledge base UI pattern

In our database backed (C# WPF / Entity Framework) application, we want to build a system to enter, store, display and search arbitrary content linked to our main entity. The challenge here is to find ...
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Viability of custom framework to serve RESTful API

Context For my end-of-year project at school I had to create a framework to serve a RESTful JSON API. I wasn't authorized to use a project like Ruby on Rails for instance, Sinatra is allowed since it ...
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91 views

What are the consequences of eliminating the ORM/ODM in a NoSQL based system?

In Martin Fowler's article OrmHate, he states the following: If you have an application problem that maps well to a NoSQL data model - such as aggregates or graphs - then you can avoid the ...
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77 views

Where do I create/instantiate repositories in DDD that are used my Domain Services

From what I understand a DomainService should be implemented against a RepositoryInterface, so we could change with easy the repository (which its a part of the Infrastructure layer) So, if I have: ...
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Do you generally send objects or their member variables into functions?

Which is generally accepted practice between these two cases: function insertIntoDatabase(Account account, Otherthing thing) { database.insertMethod(account.getId(), thing.getId(), thing....
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120 views

What functionality to expose in a database abstraction layer?

I'm trying to design a simple way of abstracting away data persistence behind an interface, but I'm having a hard time figuring out how much fine grained control should be exposed to higher layers. ...
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72 views

Best architecture for customising the character

I want to customize the game character before starting the level, for example, select what kind of weapon, armor, clothes, etc. There are several components and each component consist of several types....
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134 views

Placing preconditions in the right place

I am trying to figure out the best way to define the responsibility of checking preconditions. Let's consider the following case: we have an Event class representing a sports event and a Matchup ...
2
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1answer
77 views

What's the difference between an implementation detail and a technical concern

I just wanted to make sure that I understand and can properly articulate the difference between these two concepts. I've always thought of an implementation detail as being the internal workings of ...
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How to go about testing un-injectable code?

So I have the following piece of code in use all over my system. We're currently writing unit tests retrospectively (better late than never was my argument), but I don't see how this would be testable?...
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1answer
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Is there a good way to use the front controller pattern for command line applications?

I am a PHP developer and I used to build web applications with one PHP file per page for a very long time. This resulted in duplicated logic and messy code (even though I didn't know it at the time). ...