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

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Should we use data object (or the data transfer object) for sharing data between these three classes?

I found an article by Martin Fowler that has made me doubt my design choices, particularly about data objects. Martin Fowler has written an article about what he thinks is a code smell. In this ...
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54 views

Control (avoid) changing fields with side-effects

I have been thinking about a design problem and possible solutions in my own. I am pretty sure I am not the first one to have noticed it, but I cannot google for it since I do not know the standard ...
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Generalization of phase based systems for card and board games

In an exercise of futility I'm trying to abstract and generalize a framework where to build any turn/rule based system. I've had a head start but after decompiling HearthStone I'm second-guessing that ...
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Client vs Creator in Factory Method and Abstract Factory patterns

This page descibes one important difference between Factory Method and Abstract Factory: http://architects.dzone.com/articles/factory-method-vs-abstract The difference, according to this page, is ...
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Why do code-bases in n-tier development have an equal amount of, if not more, JavaScript code now?

I've been doing web programming for a long time now, and somewhere, I lost track of why we are doing what we are doing today (or how did we come to do things this way)? I started out with basic ASP ...
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232 views

How do you keep control in a large software project? [duplicate]

I've a large-ish software project that I'm the sole developer for (~80KLOCS and counting - I know there are much larger projects out there, but it's an order of magnitude larger than I've ever had to ...
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58 views

Duplicate method in spring services, how to refactor?

ServiceOne.java private void doStuff(){} ServiceTwo.java private void doStuff() Where to put common code ? Shall I create a new service, but then what interface will it implement ? Or shall I ...
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143 views

Designing a better performing total permissions setup for multiple permission levels

We've got a global system that we are attempting to solve a permissions issue around. Currently, our system serves a number of different applications out to our clients and each client has their own ...
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47 views

Choosing a pattern for domain logic on top of ORM model

I am using Python and ORM, particular SQLAlchmey. I have an ORM model which implements data mapper pattern. The model has a field state, which can take one of several states, let's say NEW, CANCELLED, ...
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182 views

C# structure needed for dynamic behaviour

I am using Unity to build a visualisation of a serious game. I am using the C# programming language. My problem is that I receive data from a JSON and I parse it and I end up with a list of different ...
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184 views

Program Architecture: How to manage objects that are interdependent

Consider the following case, image I making a simple chat program; I want it to be extensible such that it would be fair easy to add add different scripting and user interfaces. I want the core ...
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How and Why should class modifiers enforce or prevent inheritance and the ability to override

This isn't really related to anything I am working on currently, its more of a question I really couldn't find an answer for. Class modifiers like MustInherit or NotOverridable to me, seem like they ...
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427 views

Is factory pattern a right pattern for the situation described here?

Is factory pattern a right pattern when we want to consolidate the related objects? Problem - In the Set-top box, I have a user-io, basically the interface to control the settop box - The user-io can ...
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1answer
250 views

Is the application architecture of Facebook Flux a new idea?

Facebook announced that it's using the architecture they call Flux to develop their projects. It consists of a single direction dataflow, and concepts like a Dispatcher, Stores and Actions (well ...
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166 views

Communication between Multiple Presenters in MVP

I'm designing an application using the MVP pattern, but a few of the edge cases for the system rely on communication between multiple presenters. View 1 calls Presenter 1 which does Operation A ...
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Determining proximity of entities based on multiple measures

I have a database table set up like so: Table: entities name - varchar score - int category - varchar value - int value2 - int depth - float ... etc. Example: name ...
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265 views

Good design pattern for linq to sql

I currently have a linq to sql project that was used for one project and not much work was put into it, only the generated context and entities were used. Since then the project has started to become ...
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2k views

Is performance the only reason not to use SignalR (websockets) entirely in lieu of a traditional REST API?

I have used SignalR to achieve real-time messaging functionality in several of my projects. It seems to work reliably and is very easy to learn to use. The temptation, at least for me, is to abandon ...
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passing different models to view based on razor theme engine

I'm using a pattern similar to the one here to implement a Themed View Engine. Basically instead of having a View folder, I have a Theme folder and inside different themes: default, red, blue, green, ...
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Why use Creational patterns in Java?

How are Creational patterns useful? Most of the material I came across explains the use case to "solve common problems associated with object creation, improve flexibility". I can think of just two ...
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Software to access GSM Terminal, sending and receiving AT commands, validating results

I am currently implementing a software that uses a GSM terminal to perform actions. Actions can be sending messages, checking balance, receiving status report messages, setting the pin, ... The ...
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331 views

What is a good design pattern for multi-mode software?

I will explain my question by way of example, but I'd love a general solution. I am writing a JavaScript application that needs to function differently depending on its run-time context. To handle ...
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1answer
82 views

How to compute data for charting?

I'm building a charting component that displays data directly from the raw data records. It should be able to filter data (subset) and then perform some rudimentry maths on the data (sum, avg, etc). ...
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132 views

Should you register other services in ViewModelLocator in MVVM light?

I'm new to MVVM Light and SimpleIoC. My question is, should all the registration of view models and other services be done in the ViewModelLocator class? Or should ViewModelLocator be used only for ...
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44 views

How to clean composition root from anything other than object construction?

I'm doing poor man's DI (manual injection) in my application. My (pseudo-) composition root looks something like this: var connectionSettings = new Settings(SqlParameters) var dataLoader = new ...
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2answers
379 views

How do you apply Single Responsibility principle to a repository

I am trying to apply "SOLID" whenever I can and try to use common sense and avoid a pattern when I see that a pattern is creating more problems than it's trying to solve. I don't want to apply a ...
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642 views

Proper Model-View-_____ design

I've been reading up about Model View Controller, Model View Presenter, Model View ViewModel, and so on, and generally, the underlying concept seems pretty simple to understand: keep the pretty ...
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What is the best way to initialize a child's reference to its parent? [duplicate]

I'm developing an object model that has lots of different parent/child classes. Each child object has a reference to its parent object. I can think of (and have tried) several ways to initialize the ...
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1answer
127 views

Creating n tier application [closed]

I am new to design patterns. I want to learn constructing 3 tier architecture. I have searched but confused at some points. In this article ...
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1answer
185 views

IOC Between Presentation and Infrastructure Layer

Question: I would like to set forth dependency mapping from a *.config file from a project that has no reference to the project that contains the concrete class. Scenario: I'll be using terms from ...
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292 views

Object in Business layer same as DTO with logic?

Let's say I have a Spring MVC project, in which I'm using DTO to get data from a database and to pass data to the UI. Let's suppose that I have a UserDTO and in my business layer I have to do ...
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7answers
543 views

What is the simplest way to broadcast data from application to other applications in .Net

I want to send information from one .Net application to multiple other .Net applications. I want the applications to be loosely coupled. The number of applications receiving the information could ...
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3answers
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Interface to enumerate over files

I'm trying to design a generic interface for enumerating over a list files. Each iteration will open a file, allow the consuming code to access the file to perform some task, and then close the file. ...
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Callback pattern handling exceptions - Best practices in .NET 3.5

I am looking to implement the callback pattern with error handling such that error is caught and pass to the callback code with the response. Since I am using .NET 3.5, I cant use Task (TAP) pattern ...
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237 views

How does the consumer-producer solution work?

I'm only a beginner, and my book doesn't cover this subject. I have researched my problem and found that an implementation of the consumer-producer pattern is the ideal solution, and have Googled it, ...
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205 views

Should I couple these classes?

I am programming in Python. I have several complicated/hard-to-understand XML files that describe the structure of an election. I am trying to write a python wrapper that makes it easy to access this ...
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873 views

Should service layer catch all dao exceptions and wrap them as service exceptions?

I have three layer Spring web app: dao, service and controllers. A controller never calls directly the dao, it does it through the service layer. Right now, most of the time if there is dao exception ...
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248 views

Implements > extends, but what about variables?

It's preferable to write programs that depend on interfaces rather than on superclasses, but what when you want a class to have certain variables? Sometimes you want a class to implement a certain ...
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138 views

Should I have an object as attribute or primitive id? [duplicate]

I am wondering which principle should I use. Here is my situation. I have a class named TravelOffer. This class looks like this: public class TravelOffer { private final long id; private ...
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172 views

At what granularity are events recorded in Event Sourcing?

I'm growing my understanding of event sourcing. My understanding is that it provides a means of recording events as they happen so that given a common beginning state and an audit log of recorded ...
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1answer
145 views

What should be in a PIMPL?

I am kinda trying to implement a windowing library in C++, the circumstances are forcing me to implement it all myself, that's not the point of this question however. My question is: What should be ...
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2answers
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Designing an API with access tokens, how to handle GET requests?

I am building an API that will utilize access tokens so that I can track usage among various departments and for access control. My plan is to utilize the HTTP verbs appropriately - GET will retrieve ...
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1answer
61 views

How to save entities relations using unit of work pattern

I use Unit of work pattern to commit all new, dirty, deleted entities to the DB (using a db_mapper). Example of entities are: Student and Class So Student->registerDirty() will add this entity to ...
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167 views

Lightweight data modeling vs traditional classes [closed]

I've heard a lot of talk about using lightweight data modeling as of late. Especially in relation to the Clojure programming language. What is it and how it differs from traditional classes regarding ...
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1answer
91 views

Design Question - System Integration

Guidance on good application architecture / design is not in short supply however most of the examples focus on some business object, like Customer and its behaviour and persistence. There is little ...
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81 views

Environment that enables variable constraint checking and creation

Currently I'm working on a system that enables users to add Tag's to available TagTypes on specific pages. For instance, we would have a TagType called "Installer" and the user wants his name ...
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1answer
70 views

Where to perform datatype.ParseString (MVC)

Using the MVC pattern, asume a simple situation where you want to send a number (for example the number of pages in a book) with a controller to a setter. Now, the set method looks like this public ...
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1answer
241 views

Designing classes the right way [closed]

I am trying to design my classes in the optimal way for the following scenario. A city has metro lines covering a number of stations.There are 4 lines represented by 4 colors.The user has to enter ...
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3answers
259 views

Decorator Pattern: can it solve issues arising from changes to underlying code?

I understand that decorators solve the problem of needing to mix and match behaviors, but it was suggested that I could use the decorator pattern to solve issues of brittleness that might arise due to ...
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Is there a limitation when using the Bloch's Builder Pattern with mandatory fields?

Background I have a class TextDrawable which draws text on top of a shape. There are a number of properties that can be set while creating a TextDrawable object. Mandatory Properties: Text Shape ...