Questions tagged [design-patterns]
A design pattern is a general reusable solution to a commonly occurring problem in software design.
-2
votes
0answers
24 views
Software architecture of building a set of similar mobile applications at once [on hold]
I would like to build around 500 mobile applications that have same functionality but different design for different 500 clients at once. The applications should be totally different when they ...
9
votes
1answer
117 views
Using friend classes to encapsulate private member functions in C++ - good practice or abuse?
So I noticed it's possible to avoid putting private functions in headers by doing something like this:
// In file pred_list.h:
class PredicateList
{
int somePrivateField;
...
2
votes
2answers
73 views
Opposite pattern of Template Method
Do we have pattern, which is opposite to Template Method?
I mean, in base class we define parts of algorithm and abstract method which implements algorithm. Then in derived class, in that abstract ...
1
vote
1answer
46 views
How to propagate Setting Class throughout entire project
Here's my setup:
Entity Framework Backend
Large WPF project that has a main window with 3-4 user controls on it, each of which has 3-4 user controls on it (and so on, in some cases)
What I currently ...
5
votes
4answers
167 views
Improved design for a turn-based multiplayer game using AI?
I'm trying to decide which is the best architecture for a turn-based multiplayer game where the players can be either humans or AI and the UI is optional, for instance because the game can just be ...
0
votes
2answers
38 views
Methods taking parameter of Collection should filter the collection themselves or be passed a filtered collection?
Say I have this reasonable contrived situation:
public class Toast
{
public bool Toasted { get; set; }
public int MinutesToHeat { get; set;}
}
public class Toaster
...
2
votes
0answers
24 views
Handling field masks on the statically typed client
Let's say I have a REST API, that has the ability to provide field mask (i.e. the API can return M out of N attributes where M is a subset of N).
If a statically typed client (example: one that's ...
0
votes
1answer
49 views
Is it better to initialize semaphores in shared memory or give them as command line arguments? (C++)
I am on a project for which I have to spawn many different processes, all in different executables, and there will be some shared memory segments and some semaphores to synchronize them. I use an "...
-3
votes
0answers
56 views
How to tackle empathy based System Design interview questions? [closed]
There a lot of system design interviews which ask design question which requires a component of empathy.
For example, design a recipe app for elderly people taking input of what ingredients are ...
-3
votes
0answers
74 views
Which Design Pattern is most suitable for this problem [duplicate]
The problem states as follows:
"A Radio Station broadcasts its programs for listeners through an FM frequency, but in emergency situations the radio channel could be used as an encrypted broadcast"
...
2
votes
3answers
266 views
How correct this little game design without removing its design pattern?
Given is a design of a video game in which a player has several possibilities to adjust his character:
Game designers realized it's senseless to be a fire-elemental and water-elemental at the same ...
0
votes
0answers
26 views
WCF service contract for dynamic response based on input request. C# [closed]
Below is a sample format of response and equivalent service contract of my web service looks like.
<Players>
<Player>
<Name>Sachin</Name>
<Sport>Cricket</...
1
vote
1answer
69 views
“State” pattern and encapsulation
Suppose we have the following classes:
As you see, it's an implementation of the State Pattern.
Basically, the Order class proxies the pay() and cancel() method calls to it's concrete OrderState ...
1
vote
1answer
119 views
Java Class Design
I need to send a json response. I use the jackson library to convert the class to json. I have a core java class to which I need to add some more fields to create my json response. I came with two ...
4
votes
2answers
217 views
Injecting a dependency that is a tree of dependencies
Is it a pattern or antipattern to inject a dependency that is a tree of dependencies?
For example:
public class ClassExample
{
private IContainer _container;
public ClassExample(IContainer ...
2
votes
0answers
41 views
Data processing pipeline design for processing data
I have a use case for which I need to build a data processing pipeline
Customer contact leads data coming from different data sources like csv, data base, api has to be first mapped to a universal ...
1
vote
2answers
164 views
Clean architecture, CQRS, and authentication?
I'm working on implementing my first clean architecture and CQRS application, I've stumbled across a bit of logic that's leaving me a bit stumped. I'm working on integrating authorization and ...
2
votes
5answers
327 views
Software design pattern for class method that only should be called once
Say I have a TypeScript class:
export class TypeCreator {
entities: Set<Whatever>
registerEntities(e: Set<Whatever>): Set<Whatever>{
return this.entities = e;
}
}
if ...
0
votes
1answer
79 views
Mediator pattern across web API
What are your thoughts on mediator pattern being used from a client and across a web api?, this means:
Command definitions are shared between the client and api.
Web api exposes only one ...
2
votes
3answers
96 views
How to calculate overall progress in independent phases?
When using a call-back to show progress on a multi-phase task, I don't know how to calculate the progress per phase well. One of the phases is collecting data, which differs in size from run to run.
...
1
vote
2answers
107 views
Dependency injection in a loop?
Suppose I have a loop (in Python syntax):
xml = "<x>...</x>"
for i in arr:
j = f(x) # some complex computation
obj = Class(i, j)
xml = obj.run(xml)
Does it make sense to use ...
2
votes
0answers
62 views
Python3: How to change the design of a class hierarchy to improve access to objects there buried?
I asked this question already at stackoverflow together with a serialization related part and at codereview for the design part only. Since the design related part receives no answers or comments on ...
1
vote
1answer
64 views
Where and how to handle user password hashing in Clean Architecture?
I'm currently building a new application and trying to apply some of the principles of Clean Architecture. One of my first roadblocks is implementing my own Identity system (to avoid being tightly ...
3
votes
1answer
76 views
If your company ships multiple products, does it make sense to use a mono repo for your integration tests?
Assumption: Each product codebase is in a separate repo. If the product codebase was a mono repo, it would be a no brainer to just put them together.
Assumption: Integration tests in this context ...
2
votes
2answers
83 views
A good way to represent an object with multiple interconnected states?
I want to program a simple budget application. In my application, the budget is divided into budget periods (months by default, but it can be bi-weekly or weekly periods). In each period there is a ...
1
vote
6answers
313 views
Is it a good practice to use self-defined exception?
Our team has different opinions about the practice of using self-defined exception for handling the business logic.
Someone says it is good as the exception comes meaningful and readable, and the ...
2
votes
1answer
133 views
Is it efficient and a normal practice to have one class with thousands of lines of code? [duplicate]
I am currently in a continuous software product development project on base of legacy Java code. The source code is very complicated, which is good and bad.
But I am surprised to see that in the core ...
8
votes
2answers
146 views
fall-through switch for executing a sequence of steps
My program needs to execute a sequence of steps from start to end. But based on different input the start point will vary, e.g, some will run from the first step to end, some will run from the 2nd ...
0
votes
1answer
93 views
Decorator or Facade
I face an issue if to use a decorator or facade pattern to accomplish my needs.
Imagine a client wants to play a video. He can use the interface
public interface IVideoPlayer
{
// Prepares ...
1
vote
3answers
112 views
subclass with no logic of abstract class
I have a class named Change which should be abstract and have some basic methods.
I have classes Insert, Update and Delete that extends Change.
In the case of Insert, Update I just use extend and add ...
-3
votes
1answer
26 views
What is an integration test pattern for an extensible permutation of cases (e.g. dimensions of seed data and filtering by said dimensions)?
Suppose we have a service that returns users in certain categories, e.g.
Listens to a certain artist.
Listens to a certain playlist.
Listens to a certain genre.
Is between ages X and Y.
Is located in ...
-1
votes
1answer
188 views
Wrong use of factories in Java libraries? [closed]
Some of the Java libraries I have used so far seem to have a Factory for seemingly every other class in the library. Apache's FTP Server project, for example, provides a UserManagerFactory class which ...
2
votes
1answer
144 views
Unit Testability of Builder pattern
I'm looking at the builder pattern for helping setting up dependencies and parameters that may require complex logic for a class. But from the examples I've seen, the builder pattern does not seem ...
2
votes
1answer
81 views
Is there a name for a “multi-instance singleton pattern” — returning a reference for a same-valued object?
I am tasked to write an assembler in C, which lends itself sufficiently well in certain design-pattern scenarios, and in a parsing phase, after tokenization, I need to "fill-in" certain information ...
1
vote
1answer
57 views
Design pattern for common properties: static properties or a separate single instance class?
I need to create properties that have values common to instances of a class. I'm unsure how to solve this problem, so I could use some help. (This is in C#, but isn't a language-specific question.)
I'...
1
vote
1answer
49 views
Logging patterns from within library code
I am looking for a design pattern for logging from within library code. Suppose I have a function in a library file that i expect will be used by multiple front-ends (lets assume a CLI and a web):
...
0
votes
2answers
63 views
Singleton's applicability clarification
According to the GOF Design patterns' book, singleton pattern should be used when:
there must be exactly one instance of a class, and it must be
accessible to clients from a well-known access ...
2
votes
5answers
181 views
Design pattern for creating object hidden from client
I am having difficulty understanding which design pattern would be best for the following scenario. An application uses a database. That database can either be the production version (SQL) or a test ...
2
votes
2answers
116 views
Using injection for services that contain only pure functions
Imagine we have a service like the this:
class SomeService {
// A random pure function that transforms the input
// without doing any remote calls or any side effects
function ...
2
votes
1answer
153 views
What are the pros and cons of keeping most of an application's state in a single struct?
In my application, I have a few classes. Many of these classes share common state like a reference to the logger for example. For example, both A and B require some common state to get their job done.
...
0
votes
3answers
84 views
Dependency Injection via Constructors vs Abstract Classes
For the past few days I've been researching the relationship of abstract classes and dependency-injected via the constructor classes.
It appears that any time that I can have a dependency-injected ...
-1
votes
1answer
52 views
Design Patterns for an expression project
I have the implemented a calculator that is very similar to the following UML diagram. The only new thing is a new class, a Recognizer class, that says if the expression is written correctly or not.
...
1
vote
0answers
25 views
avoid passing dbsession object to multiple modules
I have a project which has a service-oriented architecture. for example, anything relates to payment is inside payment module.
-dao
-config
-constatnts
-middlewares
-modules
-payment
-user
-...
0
votes
0answers
92 views
Software Architecture with C# and WPF
We have the need to develop an offline desktop application for a measurement equipment.
While having quite a bit of experience in C++, We are new to WPF and VS in general.
This software will have a ...
1
vote
1answer
64 views
Managing heterogeneous data
The underlying problem is one I seem to run into a lot. You have a collection of objects with some things in common, but other information about the objects may apply to some of them but not to others....
2
votes
3answers
196 views
What are the differences between Threadpool and Object Pool patterns?
I was going through the ThreadPool pattern and it resembled the Object Pool pattern. The only difference that I can think of is that most explanation about the ThreadPool explicitly mentioned the use ...
3
votes
3answers
237 views
When to use xxxResult return value pattern?
I have one method which need to return multiple values whether it was successful or not, what the key used to call the api and if successful the return result. Here is more concrete method,
public ...
0
votes
1answer
138 views
DDD - Factory or Service?
I'm new to DDD, and I'm confused at the very start of my DDD project. To setup a context, I'm building the user management part of my app, so I'm building my Account entity, which contains an Id, a ...
1
vote
1answer
101 views
Where and how to connect to external API in my service class?
In my service class I would like to connect to external API. Where and how should I do it?
1) Inject in constructor ExternalClass and assign to private property. Next in other property in constructor ...
0
votes
3answers
95 views
Modelling recurring events
I am in the process of writing a web app to track expenses and which will be multiuser.
Everything is fine with a single expense, but I am struggling to find the best way to represent recurring ...
