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

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Is there a better way to load objects?

I have always kept the code to load an object within the object itself. That way no matter what method is creating the object, it always has access to the method to load the object. However this does ...
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42 views

Basic PHP Factory Pattern code review [migrated]

I have an object, KbArticle, that originally in it's constructor, would try to return null if the SQL query that retrieves the data for its required properties came up with 0 rows. A friend told me ...
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2answers
184 views

Repository pattern implementation that knows nothing (Jon Snow) about the database table and column names

I've seen around the Internet and Github, implementations for the design pattern Repository that knows about database table and column names. I was think, if I want to work with the database as a ...
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5answers
1k views

Is this a good practice or not?

I have a colleague who has come up with a way of 'genericizing' information from a database so that all his web application's drop-down lists can share the same object in his MVC.NET C# code and ...
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5answers
182 views

Coupling business logic with class definitions

Perhaps it is my scripting background, but my perspective is that the purpose of an object should be to contain data. Classes are necessary in that they provide templates and standard ways to classify ...
4
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3answers
473 views

What is a helper? Is it a design pattern? Is it an algorithm?

Maybe a little tongue-in-cheek, but as I can't find this answer anywhere through Google, so to ensure Programmers Stackexchange has the answer: What is a helper? I see the name being used everywhere ...
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1answer
107 views

Choosing between the view and the controller for my code

I'm aware there are a lot of topics about MVC design but it's hard to find good explanations: what I should do, what are the consequences of the different possibilities... So I'm working on an ASP ...
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77 views

How to design extension mechanism for java app

I have an application where I have a set of core features. The application itself HAS to work in core only mode. I would also want to make the application extensible such that, when certain ...
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2answers
67 views

subclass reference to another subclass

Imagine I have the following code: class A: pass class B(A): pass class C(A): def __init__(self): self.b = B() Is the above code correct in terms of correct inheritance? I ...
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1answer
82 views

What is a good strategy to develop apps that run in console and as API?

I develop quite often scripts that are primary used as a console application but later they are used in other scripts, webservices and other things where it is very convenient, to just import the ...
37
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5answers
2k views

When is Singleton appropriate?

Some hold that the Singleton Pattern is always an anti-pattern. What do you think?
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3answers
73 views

Returning results of method on batch list?

The title is a bit vague so I'll try to elaborate. I have a function makeFoo(int bar) -> returns Foo or throws Exception. I also have a batch version of this makeFoos(int[] bars) -> ...
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4answers
343 views

Adding field to the class at runtime - design pattern

Imagine your customer want's to have a possibility to add new property (e.g. color) to product in their eshop in their CMS. Instead of having properties as fields: class Car extends Product { ...
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1answer
54 views

Adding new functionality to all of shelve.Shelf's subclasses in Python

In order to avoid the overhead associated with the shelve module's writeback option I'm interested in putting together a shelf class that only accepts hashable values, with hashability being a proxy ...
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1answer
328 views

What is the good way of sharing specific data between ViewModels

We have IAppContext which is injected into ViewModel. This service contains shared data: global filters and other application wide properties. But there are cases when data is very specific. For ...
2
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1answer
89 views

How do you show the exception handler in a class diagram?

I have one exception handler class. I want to show this class in the uml -- class diagram. But, I do not know how to represent relationship between class <X> and exception handler class. How can ...
35
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11answers
4k views

Are error variables an anti-pattern or good design?

In order to handle several possible errors that shouldn't halt execution, I have an error variable that clients can check and use to throw exceptions. Is this an Anti-Pattern? Is there a better way to ...
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1answer
75 views

Confused on how to properly employ a Repository Pattern with Service/Business Layer on top

I'm building a ASP.NET Web Api 2 solution for learning purposes, and I've hit a snag. I was wondering if anyone could tell me what exactly it is that I'm missing. My Web Api solution has 4 Layers: ...
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1answer
306 views

Why use Android Fragments?

I have read the documentation and some other questions' threads about this topic and I don't really feel convinced; I don't see clearly the limits of use of this technique. Fragments are now seen as ...
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77 views

Result Object vs. Exceptions [on hold]

Related to this question I posted earlier: Returning results of method on batch list? I stumbled across an interesting idea at: https://www.braintreepayments.com/docs/java/general/result_objects ...
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2answers
126 views

How to present a stable data model in a public API that allows internal data structures to be changed without breaking the public view of the data?

I am in the process of developing an application that allows users to write C# scripts. These scripts allow users to call selected methods and to access and manipulate data in a document. This works ...
2
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1answer
67 views

Use adapter pattern for coupled classes

I need (for unit testing purposes) to create adapters for external library classes.ExchangeService and ContactsFolder are Microsoft's implementations in its' EWS library. So I created my adapters that ...
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0answers
106 views

MVC content management framework with an admin panel

I've lately been developing my own MVC content management system using PHP and, at least in my mind, am a little stuck with the system design. I believe this would apply to building a content ...
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1answer
71 views

Implement Generic DataSet Builder with C#

I want to create a data access library that can build a DataSets with relations which can easily be written to XML with dataset.WriteXML(). This is a get to know C# endeavor that will hopefully gain ...
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1answer
155 views

implementing dynamic query handler on historical data

EDIT : Refined question to focus on the core issue Context: I have historical data about property (house) sales collected from various sources in a centralized/cloud data source (assume info ...
2
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1answer
253 views

Javascript Implementation Patterns for Server-side MVC Websites

I'm looking for information on common patterns for initializing and executing Javascript page by page in a "traditional" server-side MVC website architecture. A few months ago, my development team ...
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1answer
213 views

Email Content creation | Proper design

Working on an E commerce application where we need to send so many email to customer like Registration email Forget Password Order placed There are many other emails that can be sent, I already ...
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1answer
89 views

Freeing Memory: Observer Pattern?

I am building a scientific application in matlab which handles several hundred large matrices (large as in 'very few of these will fit into ram'). Each matrix is contained within a dedicated object to ...
3
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1answer
47 views

Pattern to use to relate multiple data sources to different user data widgets

I have an client x server intranet application the basically gets data from the server, format it and send that data to the client for display. At the server we are using ASP.NET C# running on IIS ...
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95 views

Real world Programming [closed]

When starting a new project are design patterns useful way of coding for rapid prototyping (small scale projects) or are they for production (full blown projects) or for all cases?
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8 views

Select design pattern - user stage [duplicate]

I'm struggling to point a finger into the right design pattern. I have a web site which user can register and interact with the system. I want to add the following abilities to a user: Each user ...
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2answers
85 views

Select design pattern - user stage

I'm struggling to point a finger into the right design pattern. I have a web site which user can register and interact with the system. I want to add the following abilities to a user: Each user ...
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1answer
392 views

Design Pattern for Data Validation

What would be the best design pattern for this problem: I have an Object A. Object A can either be registered or deleted from the database depending on the user request. Data validation is performed ...
48
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2answers
4k views

Are there any OO-principles that are practically applicable for Javascript?

Javascript is a prototype-based object oriented language but can become class-based in a variety of ways, either by: Writing the functions to be used as classes by yourself Use a nifty class system ...
2
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1answer
185 views

Design Patterns for creating tasks

I am developing software where each action in my entities need create tasks that will be execute in my infrastructure. When I create a task it is only records in the database. Afterwards, a windows ...
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1answer
22 views

Store Arbitrary values related to mysql record

I have created an app that manages a Data cleansing workflow. Each row imported needs to store an arbitrary number of key value pairs in addition to our standard mysql schema. The key values need to ...
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3answers
436 views

Functional programming strategies in imperative languages

I've been convinced for awhile now that some strategies in functional programming are better suited to a number of computations (i.e immutability of data structures). However, due to the popularity of ...
4
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2answers
536 views

Acceptable placement of the composition root using dependency injection and inversion of control containers

I've read in several sources including Mark Seemann's 'Ploeh' blog about how the appropriate placement of the composition root of an IoC container is as close as possible to the entry point of an ...
3
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3answers
574 views

design practice for business layer when supporting API versioning

Is there any design pattern or practice recommended for business layer when dealing with multiple API version. For example, I have something like this. http://site.com/blogs/v1/?count=10 which ...
0
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1answer
72 views

DTO - service layer - statelessness best practices interfering with each other

I am designing a REST API coupled with a service layer that takes DTOs as input and produces them as output. This works fine for most service calls where the DTO is used to access an underlying ...
2
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1answer
406 views

A small project but I want to use design patterns to do it right

I've got a project coming up, a very a small system, but one that needs to be extended in the future. Here's how I've designed it so far. It's 3-tier: presentation, business and data. For the ...
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1answer
288 views

Android design advice - services & broadcast receivers

I'm in the process of learning the Android SDK and creating some projects to get a grasp on the system. The current project I'm working with works just fine but I'd like to get some advice about ...
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2answers
144 views

Good architecture for passing data to multiple APIs

I have a hypothetical scenario where I need to pass data to APIs from multiple different providers, depending on the 'vendor identity' provided by one of the pieces of data. If I have the data as ...
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2answers
131 views

Optimization ended up in casting an object at each method call

I've been doing some optimization for the following piece of code : public void DrawLine(int x1, int y1, int x2, int y2, int color) { _bitmap.DrawLineBresenham(x1, y1, x2, y2, color); } After ...
82
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10answers
31k views

What is MVC, really? [closed]

As a serious programmer, how do you answer the question What is MVC? In my mind, MVC is sort of a nebulous topic — and because of that, if your audience is a learner, then you're free to ...
0
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1answer
66 views

Implement RPC via SIP

Look at the following use case. I have a client (Java) application, which wants to get/set the state of another, remote application (C). The communication between them is done via SIP, which is run ...
3
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2answers
230 views

Is the Java Integer cache a realization of the object pool pattern?

One of the best-known examples of a full-fledged object pool is the JDBC connection pool. Main reasons: objects in the pool are expensive to create and relate with external resources each object in ...
0
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1answer
110 views

How to design a scriptable communication emulator?

Requirement: We need a tool that simulates a hardware device that communicates via RS232 or TCP/IP to allow us to test our main application which will communicate with the device. Current flow: ...
0
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0answers
25 views

API providing function to be run in a thread vs. thread that runs this function

I'm writing a Python library which exposes a certain event listener interface. The user can register callbacks to handle different types of events. There is also a function which handles the actual ...
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0answers
28 views

update methods in simple factories

I have simple factory class with differently named methods which create the same object but differently. These created objects are persisted to db. These are then retrieved from the db elsewhere and ...