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

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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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63 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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200 views

Am I following a good design thought process? Is the Abp framework overkill?

As I finish one project and start another, I have a small time window to come up with an architecture for the new. I am coming from the following design: Web applicationReceives domain models & ...
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153 views

The finer points of HMVC

I'm new to HMVC and whilst tutorials are great about dealing with the overall details of keeping modules separate and only letting controllers communicate, they aren't so great at explaining the ...
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261 views

What is a good way to structure my UI classes?

So, I have a program which has a swing GUI. (Java - duh!) I really, really don't think the way I'm structuring my classes now is good, so I am reorganizing from the ground up to follow best practices. ...
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160 views

How to validate information on server without using database or session

Each user has multiple sites they can access reporting data for in an application I am working on. To prevent having to go to the database on every single request, I validate that they have access to ...
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35 views

Passing configuration to a handler

I'm building my own JET Parser and one of the things I am trying to do as per the JET specifications is to allow changing of the start and end tags from the default <% and %>. Right now I have ...
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331 views

NCurses, scrolling of multiline items, “current item” pointer and “selected items”

I am looking for hints/ideas for the best (most effective) way on how to scroll multi-line items as well as emphasizing of the "current item" and "selected items" such as: 1 FOO ITEM 1 Foo sub-item ...
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1answer
181 views

Is this considered an implementation of the Template Method design pattern? [closed]

Please consider a StringBank class. This class holds a list of Strings and can return them to the client. It's code (irrelevant stuff omitted): abstract class StringBank{ List<String> ...
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2answers
864 views

Correct way to inject dependencies in Business logic service?

Currently the structure of my application is as below Web App --> WCF Service (just a facade) --> Business Logic Services --> Repository -> Entity Framework Datacontext Now each of my Business logic ...
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72 views

Modelling network and persistent entity representations

I have an app where I need to synchronize some entities (simply download latest versions of entities from server to client). Entity has bunch of text properties and bunch of resource links (referenced ...
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292 views

Can this argument be enough?

We have two C++ classes named Important and Small The class Small use a few methods and attributes from the class Important, but not all. Since our application is performance critical, instead of ...
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774 views

Implementing a strategy pattern with dependency injection

Okay, so the goal here is to implement a strategy pattern that can be tested using any sort of automated testing tool. I've been struggling with this problem conceptually for a few weeks now and I ...
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129 views

Looking for design pattern to represent shared state in music sequencer

I like to give lots of context, but also to state the basic question up top as concisely as possible. Feel free to read a little or a lot. I'm working on a music sequencer, and have been happy so far ...
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34 views

SPA thin or thick architecture [duplicate]

I seek your advice on SPA (Single-page application) architecture. I'm building an SPA which edits a model. The models consists of objects which have a relation to one another. The objects (and ...
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79 views

Creating classes according to a struct

I get a array via SOAP service, in the array in each value which is a struct is a description of any visual components (size, position, default value etc.) like CheckBox, RadioButton etc. And I wonder ...
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885 views

Syncing client and server CRUD operations using json and php

I'm working on some code to sync the state of models between client (being a javascript application) and server. Often I end up writing redundant code to track the client and server objects so I can ...
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1answer
361 views

Design pattern for locking asynchronous operations in Objective-C

I'm writing my first Objective-C Class. It's responsible for interaction with an HTTP SSO authentication service. The process requires multiple HTTP transactions in order to complete. The Class acts ...
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177 views

Pattern or solution for using classes with different interface the same way

What I would like to achieve is to use classes (now two, later more) with different interface the same way, so I would like avoid using decisions based on the interface on upper levels for instance, I ...
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1answer
186 views

Component design: getting cohesion right

I currently have a set of components named DataValues, ValueParsers, ValueFormatters and ValueValidators. The first one defines an abstract base class DataValue and contains a whole load of ...
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146 views

Using a Finite State Machine for access management?

My intranet site uses LDAP and Active Directory to authenticate users. There are 2 kinds of Users: Managers and Employees. They are differentiated by having membership in a particular AD group. In an ...
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25 views

Re-architecting a classic inheritance design [duplicate]

I have the opportunity to rewrite a core piece of a project that is inheritance-heavy and feels increasingly restrictive in how it is designed. The scenario is pretty simple, imagine an application ...
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2answers
752 views

Converting Business Process Maps into Software

I am fairly new to web application development. I have defined my problem domain through talking to various stakeholders and putting a process map together - basically a flow chart showing the ...
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2answers
367 views

Client Server .NET application with queuing message

I am new, so forgive me if my question is mistaken or anything, just give me an alert and I'll be glad to fix it. Me and my team is about to develop a system where the database is located in a ...
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2answers
609 views

Class structure/pattern for validating several different Excel templates?

I'm trying to validate the contents of Excel sheets that follow several different templates. For each one, there are three possible validation actions for various cells: Regex (e.g. "XYZ-123" fails ...
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1answer
2k views

Use decorator and factory together to extend objects?

I'm new to OOP and design pattern. I've a simple app that handles the generation of Tables, Columns (that belong to Table), Rows (that belong to Table and have Columns) and Values (that belong to ...
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192 views

Build filter conditions for entities on client side

I have the requirement that users should be able to specify filter conditions for one kind of entity through a GUI on a thin client. These conditions must be convenient to generate, meaning the GUI ...
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1answer
5k views

Implementing a ILogger interface to log data

I have a need to write data to file in one of my classes. Obviously I will pass an interface into my class to decouple it. I was thinking this interface will be used for testing and also in other ...
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205 views

Main class passes dbConn obj to all its services, I need to change the dbConn for one of its services. - suggestion for design pattern

There is this main class and there are several services ( which uses db connection to retrieve data ) These services are initialized in the main class db properties are obtained from the property ...
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1answer
2k views

What is the best design pattern for asynchronous message passing in a Chrome extension?

I have a background script that is responsible for getting and setting data to a localStorage database. My content scripts must communicate with the background script to send and receive data. Right ...
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1answer
237 views

Pattern for a web application

I'm developing a web application for a university project. My professor wants we to use a multi-tier architecture (Client, Web, Business and Data tiers) with EJB. For the Web and Business I have ...
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1answer
340 views

Designing classes containing the same objects but different amount of them

I am creating a main object, MACHINE, which will contain a diversity of several other objects -- AXIS, AMPLIFIER, ENDEFFECTOR, etc. The number of contained objects will vary depending on the MACHINE ...
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2answers
132 views

MVC - Database search logic in View or Model

Special Note: I asked a very similar question on Stack Overflow, but I have since decided the problem should be solved from a design standpoint rather than an implementation standpoint. I have ...
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1answer
462 views

Design pattern where decorated object may ask for things like “status updates” from the decorator to perform it's role?

Here's an situation that has haunted one of my open-source projects for quite some time. Imagine if you could represent every front-end input form with a single backend object? An object that ...
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3answers
407 views

Best OOP pattern to use for creating a commandline SQL API for a proprietary json based company datastore

We need to create a SQL commandline tool for querying a proprietary json based datastore. I'll be using java. Any suggestions on the primary OOP design pattern I should use for building this API? ...
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568 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
256 views

Create an Objective-C category to route methods depending on a specified type

For one project, I needed to find a solution to avoid code like this: if ([self.desiredColor isEqualToString:@"Red"]) [self constructRedMenu]; else if ([self.desiredColor ...
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2answers
355 views

Modeling an extensible Domain Driven Design project

Say that we are developing an application with modules (Sales, Accounting, Purchasing, etc). An example case here is : Sales module is the basic / primary module available, and Accounting module is ...
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1answer
335 views

Creating a System Sequence Diagram from an [extended] use case

As I have been taught - one controller = one use case. But I have: OutsiderController SupplierController (which extends OutsiderController) SubContractorController (which also extentds ...
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5answers
517 views

what's the name of this pattern?

I see this a lot in frameworks. You have a master class which other classes register with. The master class then decides which of the registered classes to delegate the request to. An example based ...
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3answers
496 views

Eliminate duplicate code in nested IFs without creating a function [duplicate]

Let's say we have two ifs that depend on each other: if var exists { if var is array { //Do stuff with var } else { //Resolve the problem } } else { //Resolve the ...
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2answers
533 views

Does the pattern of passing in one object instead of many parameters to a constructor have a name?

If you have a constructor that takes a lot of parameters, like this: public OrgUnitsHalRepresentation(List<OrgUnitSummaryHalRepresentation> orgUnitSummaryHalRepresentationList, int count, ...
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3answers
189 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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4answers
412 views

Why design pattern is not named as implementation pattern?

I find that most of the design patterns are concerned with implementation of a model like mvc, or how to change the implementation with less cost. These are all happened in the implementation phase of ...
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2answers
175 views

Design Patterns: What design pattern should I use for the following? [duplicate]

I am trying to write an utility which traverses through a list of files and searches for a string in each file. On finding the string in a file, I will add it to a list and display the list. Which ...
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4answers
1k views

which pattern is most intuitive for a calculator app?

The title says it all. I'm trying to build a calculator application (for self-learning purposes). The application is going to have a very common UI, with plus(+), minus(-), multiply(*) and a divide(/) ...
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2answers
3k views

Model-View-Controller — Where does a factory class go?

I'm working (slowly) on a small Flask project. One of my models is a class called Post, which is a lightweight namedtuple. Post objects are created by a PostFactory, because creating a Post involves ...
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4answers
276 views

Fixing class Hierarchy design mistakes due to incorrect inheritance

I have a code like this. My derived class man, may not properly have a member function declared pure virtual higher up the hierarchy. eg. WagTail here class mammal{ public: virtual void WagTail() ...
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4answers
302 views

2 methods that are 75% the same? [closed]

I have code that violates the DRY principle and I would like to consolidate 2 methods as much as I can, but the problem I am facing is that they have some differences, I would say they are about 75% ...
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742 views

Is it bad to use DI to inject constructor parameters at runtime?

These are two classes, the first one I inject an instance of type IEngine while the second one I inject owner's name, tickets and engine. Version 1: public class Car { public Car(IEngine ...