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

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Where to keep persistent services in MVVM architecture?

In an MVVM application I need to use some services that are persistent, e.g. network services like P2P and WCF where the main "engine" or server endpoint must remain up and running during the lifetime ...
2
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1answer
118 views
+100

Application development with fully dynamic controls and processes based on database

All software development projects are moving into separation of design, logic , data in patterns like MVC , MVVM and others. Strangely i got a very strange requirement for a new software; that is : ...
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4answers
1k views

Is it a good practice to wrap all primitives and Strings? [duplicate]

According to Jeff Bay's Essay on Object Callisthenics, One of the practices is set to be "Wrap all primitives and Strings" Can anyone elaborate on this ? In languages where we already have wrappers ...
2
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1answer
201 views

Class becoming God Object what pattern to use

I am developing Android app and my MainActivity is becoming God Object. By the way native Activity class implementation is some sort of God Object already. The problem is that my activity class is ...
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84 views

how can the presenter or view interact with the model in the MVP pattern?

I'm learning the MV* patterns. MVP in this case. I'm trying to refactor an old android application into the MVP pattern to make things less tightly coupled, but I'm struggling one one concept. I know ...
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27 views

Design pattern identificaiton and improvement

QUESTIONS: What is the name/style of the design pattern I am using by my use of the value property/attribute/method on each class? Is there another/more appropriate design pattern that I should ...
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2answers
269 views

implementing dynamic query handler on historical data

Context: I have historical data about property (house) sales collected from various sources in a centralized/cloud data source (assume info collection is handled by a third party) Planning to ...
2
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3answers
117 views

How to use one web page to create and edit database entries

My team and I are developing a java web application which allows our admins to create and edit "methods" which can later be viewed by other users. We are currently discussing the best way to ...
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3answers
113 views

Design Pattern - DLL per Strategy

I usually found myself designing my application in the following way: One DLL containing interfaces for a desired subsystem. For example, Company.Framework.Persistence.dll. One new DLL per each ...
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1answer
229 views

What is the best way to create DTOs from entities and update entities from DTOs in a layered architecture?

Option 1: At first I would make a call to my service layer, which served as an API for my core domain, to get a domain object or a list of domain objects and then pass them into the assembler which ...
2
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2answers
240 views

Is this the solution to static inheritance?

I've seen a lot of posts recently on why Singletons should be avoided. However, I can't see any of those problems with the following solution to a common problem: static inheritance. For example, I ...
3
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1answer
306 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 ...
0
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2answers
85 views

in trouble making a card game with pygame

I am designing a card game playable against the computer. The rule is very simple Both player and CPU gets 10 cards of 1 to 10. Player and CPU plays a single card at the same time, every round. The ...
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4answers
1k views

Avoid having an initialization method

I have this existing code where they have a class and an initialization method in that class. It is expected that once the object of the class is created, they need to call initialize on it. Reason ...
1
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1answer
123 views

Best solution to switch between new and deprecated code

We have a feature that is currently implemented, let's call it implA. ImplA works but can't do many things. So we have decided to rewrite it. But we can't just replace it right away, so we will need ...
0
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2answers
80 views

Middleware dependencies

I'm trying to convert a legacy PHP app to use the middleware paradigm, similar to connect/express.js. I've started porting the code into separate middlewares so that every feature is neatly self ...
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0answers
33 views

Command Pattern for Logging/Backup/Testing

I need your input guys on this concept I intend to implement: Use the Command Pattern to record everything in my app. It should encapsulate every single user action and micro-action as a Command and ...
0
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1answer
47 views

Design pattern for mapping data fields

I have seen this problem a few times and never can come up with a solution i like. System A Sales Order Entity order_id created line_items_count System B Sales Order ...
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3answers
212 views

Decorator design pattern in swift

Im reading "Head first design patterns" (here you can find exact example mentioned in book) While going through Decorator design pattern, everything was crisp and clear until i stumbled into this ...
3
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3answers
142 views

What is the most efficient way to find a set of locations within a radius of a certain point?

Imagine a dataset of all the restaurants in the US (similar to Yelp, etc), how would you return a set of restaurants within a certain range of a particular zip code. (Assuming you have already a ...
0
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0answers
62 views

Addicted to Interfaces - Good or bad? [duplicate]

After 2 years of programming, I usually found myself using the following design pattern: public interface ISomeInterface { void SomeMethod(); void OtherMethod(); } public abstract class ...
0
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1answer
93 views

Design pattern for ensuring the “signature” of generic lists is equal

I have an interface, Attribute, that is going to be implemented in various ways, class AttributeA implements Attribute{\\..} class AttributeB implements Attribute{\\..} Then I'm planning to have ...
4
votes
3answers
158 views

Design patterns for implementing optionally supported features

Here's the original problem. There are two classes: Protocol and, say, ProtocolUser (which actully uses the Protocol class instance). Now, I need to support multiple protocols, whose feature sets only ...
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1answer
56 views

Efficiently extracting data from pdf with a template system?

basically allow a user to label specific text in a pdf file. Use the label information to create a template, which a script uses to extract text from specific pdf. What would be a good pattern to use ...
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2answers
255 views

Sharing code logic between controllers, through the Model layer?

As I originally conceived my Model layer, it was only supposed to hold data and no code. I receive DTOs from web-services, they are mapped into my Model objects. Those model objects usually end up ...
0
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2answers
539 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 ...
3
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4answers
1k views

How to force “program to an interface” without using a java Interface in java 1.6

In java 1.8 they have wonderful new "default interface methods". In 1.6 how close can we come? The goal: use code to keep clients from being able to tell that a class is not a java interface. If we ...
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2answers
94 views

How can I have objects interacting and communicating with each other without forcing a hierarchy?

I hope these ramblings will make my question clear — I'd totally understand if they wont, though, so let me know if that's the case, and I'll try making myself clearer. Meet BoxPong, a very ...
14
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4answers
17k views

Should angularjs directive directly interact with services or is it considered an anti-pattern?

Which one is considered better: having a directive that interacts with services directly or having a directive that exposes certain hooks to which controller may bind behaviour (involving ...
2
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1answer
203 views

When do I reuse or create a new Builder

I've implemented a Builder Pattern in a project I'm working. I'm using this design pattern to created Fields and Components (div, tables, panel (boostrap)). So I have a Director Component class. It ...
2
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1answer
279 views

Change routing to comply with Law of Demeter

I have a Task, Owner and Plan. Charge values are kept in a plan, owner is on a particular plan and task knows its owner. A task needs to setup its charges based on the knowledge the owner has. Owner ...
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0answers
43 views

Android, access 1 activity from 2 cases, what design pattern is this?

I'm developing an Android app, encounter this case. There are 2 ways we can enter an activity (named activityB): either from activityA or from notification. 1st case: ActivityA -> activityB 2nd ...
28
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5answers
1k views

Amateur question about corrupt software [closed]

I was hoping someone here could help a non-coder with just a few questions to give some realism to a no-budget film. I am currently writing a screenplay in which the main character's analytic ...
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2answers
101 views

Are the Repository Pattern and Active Record pattern compatible?

Currently I am developing a webapp where I have defined models implementing the Active Record pattern. Each model also is defined by an interface that specifies the Entity properties and makes it easy ...
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2answers
127 views

Designing Message class in Java

I'm writing a class for Message. Message comes with Header and Payload. Header has following fields: Version Type For Type "XYZ", the following Payloads are allowed. Configuration Metafile ...
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2answers
81 views

What is the better way of getting different outputs for two very simmilar related workflows

I have a very concrete scenario but I think it would be quite frequent. I'm trying to come up with a solution that it's "better" by better meaning more scalable, reusable and not smelly. I'm working ...
3
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3answers
104 views

Would implementing a “Throwable Event System” be abusive?

I have been thinking for a couple years now about using Throwable events and implementing a sort of event system that uses throw to dispatch an event, or let a different method handle it with throws. ...
9
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4answers
511 views

Is Visitor Pattern valid in this scenario?

The goal of my task is to design a small system which can run scheduled recurring tasks. A recurring task is something like "send an email to administrator every hour from 8:00 am to 5:00 pm, Monday ...
1
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2answers
87 views

In javascript, should object properties be declared on top of the function?

I learned that it's good practice to declare variables before they are used. For example: function myFunction() { var i; var j; } Does the same thing go for object properties, and is there a ...
1
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1answer
48 views

File validation rules

I have an application that can accept CSV files to run some operations. The files look like: CREATE USER:username,last_name,first_name,age user1,Smith,John,23 user2,Poppins,Mary,257 There are a ...
1
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1answer
308 views

What is better repository design?

I have tables that I insert, delete and update, but I read from views. At times, I may read from the tables as well. What is a better generic interface for a Repository: public interface ...
4
votes
1answer
389 views

Which patterns/architecture to apply for “Import Data, Process Data, Export Result”

I was wondering which architecture/patterns to choose for the following problem divided into three steps: Import TestScript Description from File (e.g. .xls, .txt) Process Described TestScript ...
2
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2answers
632 views

Repository pattern implementation that knows nothing 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 ...
1
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1answer
115 views

Differences in design/thought process for OO in Java and JavaScript [duplicate]

Despite sharing a similar name and syntax, Java and JavaScript are quite different. However, they both have Object Oriented features. As a JavaScript novice, the main differences that I can see ...
54
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3answers
7k views

What is the “Free Monad + Interpreter” pattern?

I've seen people talking about Free Monad with Interpreter, particularly in the context of data-access. What is this pattern? When might I want to use it? How does it work, and how would I implement ...
3
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1answer
69 views

Encapsulating mutable objects with special structure in Python

I am writing a library for working with special types of trees, called Foo trees. A Foo tree has very special structure. There some operations, called bar and baz, which only make sense on Foo trees. ...
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2answers
203 views

which one is recommended object-oriented design? [closed]

I made simple object-oriented prgram, and think about design. I wonder which one of belows is recommended object-oriented design. Most left side class is "Main" class. Black arrow means they are "Has ...
2
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2answers
192 views

Problems with OO design for application with pluggable components

I'm trying to refactor an ugly code and make it easly extendable in the future. The application should be nothing else but a series of components that have input(s) and output(s). The components ...
6
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1answer
442 views

Can Test-Driven development work in legacy projects?

So here is a question for you, having read some great answers to questions such as Test-Driven Development - Convince Me. So my question is: "Can Test-Driven Development be used effectively on ...
3
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3answers
158 views

Design suggestions for converters in Java

I'm trying a set of converters which will convert an object to some older form. And there are different objects which are converted. By older form I mean changing the values of some fields and in case ...