Object-oriented design is the process of planning a system of interacting objects for the purpose of solving a software problem.
2
votes
6answers
752 views
What are abstract classes and abstract methods?
I got several explanations but so far I'm not able to understand that what are the abstract classes and methods in Java.
Some said it has to do something with the security of the program, other said ...
1
vote
3answers
190 views
Inheritance from the objects themselves
Making new inheritance hierarchy with the help of C++ I think about:
Why there is no inheritance from the class objects? Abstract example (on abstract C++):
struct Foo { int v; Foo(int a) : v(a) ...
0
votes
1answer
211 views
Liskov substitution and abstract classes / strategy pattern
I'm trying to follow LSP in practical programming. And I wonder if different constructors of subclasses violate it. It would be great to hear an explanation instead of just yes/no. Thanks much!
P.S. ...
0
votes
0answers
190 views
How to learn to deliver quality software designs when working on a tight deadline? [closed]
I read many books about how to design great software, but I kind of struggle to come up with a good design decisions when it comes to business apps, especially when the timeframe is tough.
In the ...
0
votes
1answer
74 views
Objected oriented approach to structure inside structure [closed]
This is for C++ but should apply to any OO language.
Trying to figure out the correct object oriented apporach to do the following (this is what I do in C).
struct Container {
enum type;
union {
...
3
votes
3answers
258 views
Override methods should call base method?
I'm just running NDepend against some code that I have written and one of the warnings is Overrides of Method() should call base.Method().
The places this occurs are where I have a base class which ...
2
votes
2answers
782 views
How to design a scalable notification system? [closed]
I need to write a notification system manager.
Here is my requirements:
I need to be able to send a Notification on different platforms, which may be totally different (for exemple, I need to be ...
1
vote
3answers
187 views
OOD: All classes at bottom of hierarchy contain the same field
I am creating a class diagram for what I thought was a fairly simple problem. However, when I get to the bottom of the hierarchy, all of the classes only contain one field and it is the same one.
...
3
votes
4answers
232 views
Representing complex object dependencies
I have several classes with a reasonably complex (but acyclic) dependency graph. All the dependencies are of the form: class X instance contains an attribute of class Y. All such attributes are set ...
1
vote
1answer
261 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 ...
3
votes
2answers
290 views
Too complex/too many objects?
I know that this will be a difficult question to answer without context, but hopefully there are at least some good guidelines to share on this. The questions are at the bottom if you want to skip the ...
0
votes
2answers
216 views
Examples of Liskov Substitution [closed]
I'm facilitating a session next week on the Liskov Substitution Principle and I was wondering if anyone had any examples of violations 'from the trenches'? I'm looking for something other than uncle ...
6
votes
4answers
232 views
Do functional generics exist and what is the correct name for them if they do?
Consider the following generic class:
public class EntityChangeInfo<EntityType,TEntityKey>
{
ChangeTypeEnum ChangeType {get;}
TEntityKeyType EntityKey {get;}
}
Here EntityType ...
0
votes
1answer
117 views
would a composite design pattern be useful for group membership?
I'm trying to think about the best way to handle group memberships on a website. People sign up and select checkboxes in a list of interests. Every week we send out interest-themed emails to those ...
1
vote
3answers
187 views
Should I use an interface when methods are only similar?
I was posed with the idea of creating an object that checks if a point will collide with a line:
public class PointAndLineSegmentCollisionDetector {
public void Collides(Point p, LineSegment s) {
...
1
vote
2answers
268 views
REST API wrapper - class design for 'lite' object responses
I am writing a class library to serve as a managed .NET wrapper over a REST API. I'm very new to OOP, and this task is an ideal opportunity for me to learn some OOP concepts in a real-life situation ...
2
votes
2answers
120 views
Strategies for invoking subclass methods on generic objects [duplicate]
Possible Duplicate:
Alternatives to type casting in your domain
I've run into this issue in a number of places and have solved it a bunch of different ways but looking for other solutions ...
4
votes
6answers
172 views
Where should I put a method that returns a list of active entries of a table?
I have a class named GuestbookEntry that maps to the properties that are in the database table named "guestbook". Very simple!
Originally, I had a static method named getActiveEntries() that ...
6
votes
6answers
2k views
What are the differences between abstract classes, interfaces, and when to use them
Recently I have started to wrap my head around OOP, and I am now to the point where the more I read about the differences between Abstract classes and Interfaces the more confused I become. So far, ...
0
votes
2answers
148 views
When modeling a virtual circuit board, what is the best design pattern to check for cycles?
To make it simple assume you have only AND and OR gates. Each has two inputs and one output. The output of two inputs can be used as an input for the next gate For example:
A AND B -> E
C AND D -> F
...
4
votes
1answer
278 views
Why doesn't Java's BigInteger class have a constructor capable of taking a numeric literal? [closed]
Why doesn't Java's BigInteger class have a constructor capable of taking a numeric literal? Every single time I use BigIntegers, and many times I merely think about them, I wonder this.
What reason ...
3
votes
3answers
477 views
What kind of programs/solutions can only be written with OOP or are too hard to achieve without it? [closed]
Paraphrasing a recent question: What is Object Oriented Programming ill-suited for?
I would like to ask the opposite question:
What kind of programs cannot be written unless you use OOP?
What kind ...
2
votes
2answers
154 views
design a model for a system of dependent variables
I'm dealing with a modeling system (financial) that has dozens of variables. Some of the variables are independent, and function as inputs to the system; most of them are calculated from other ...
3
votes
2answers
582 views
DB Object passing between classes singleton, static or other?
So I'm designing a reporting system at work it's my first project written OOP and I'm stuck on the design choice for the DB class.
Obviously I only want to create one instance of the DB class ...
5
votes
1answer
156 views
Object oriented wrapper around a dll
So, I'm writing a C# managed wrapper around a native dll. The dll contains several hundred functions. In most cases, the first argument to each function is an opaque handle to a type internal to the ...
17
votes
4answers
751 views
Do unit tests sometimes break encapsulation?
I very often hear the following: "If you want to test private methods, you'd better put that in another class and expose it."
While sometimes that's the case and we have a hiding concept inside our ...
10
votes
7answers
1k views
What can go wrong if the Liskov substitution principle is violated?
I was following this highly voted question on possible violation of Liskov Substitution principle. I know what the Liskov Substitution principle is, but what is still not clear in my mind is what ...
53
votes
6answers
3k views
Is this a violation of the Liskov Substitution Principle?
Say we have a list of Task entities, and a ProjectTask sub type. Tasks can be closed at any time, except ProjectTasks which cannot be closed once they have a status of Started. The UI should ensure ...
1
vote
1answer
109 views
Object behaviour or separate class?
When it comes to OO database access you see two common approaches - the first is to provide a class (say "Customer") with methods such as Retrieve(), Update(), Delete(), etc. The other is to keep the ...
44
votes
10answers
2k views
My proposed design is usually worse than my colleague's - how do I get better?
I have been programming for couple of years and am generally good when it comes to fixing problems and creating small-to-medium scripts, however, I'm generally not good at designing large scale ...
4
votes
3answers
620 views
How to avoid javascript becoming spaghetti code?
I've done quite a lot of javascript over the years and I'm using a more object-oriented approach, specifically with the module pattern. Which kind of approach do you do use to avoid a bigger code-base ...
1
vote
2answers
60 views
Making a design for a Problem [closed]
I have written many codes using OOPS and I am still to understand when is a code good enough to be accepted by experts. The thought procedure of every man is different and so is the design. My ...
1
vote
3answers
209 views
Any tips/tricks/resources on actually TEACHING a class on OOP? [closed]
I may slowly be getting into teaching an Object-Orientated Programming class at my school in a year or two. I just graduated and work at my school as an Application Programmer. I'd first start off as ...
2
votes
1answer
137 views
How can I design my classes to include calendar events stored in a database?
I'm developing a web calendar in php (using Symfony2) inspired by iCal for a project of mine.
At this moment, I have two classes: a class "Calendar" and a class "CalendarCell".
Here you are the two ...
2
votes
1answer
159 views
Finding the best practice for a game simulating tool
I'm studying Java right now, and I'm thinking of this tool as my practice project.
The game is "League of Legends" in case anyone knows it, I'm not actually simulating the game as in simulating game ...
3
votes
1answer
231 views
The Meaning of Unified in UML
UML and other related modelling languages are exists in most of the system engineering fields to represent the system, flow, relations in a structured way. UML also is one of the modelling language ...
4
votes
3answers
278 views
What is a good design model for my new class?
I am a beginning programmer who, after trying to manage over 2000 lines of procedural php code, now has discovered the value of OOP. I have read a few books to get me up to speed on the beginning ...
19
votes
6answers
840 views
Should an object know its own ID?
obj.id seems fairly common and also seems to fall within the range of something an object could know about itself. I find myself asking why should my object know its own id?
It doesn't seem to have a ...
12
votes
3answers
2k views
Where to put business logic in MVC design?
I have created a simple MVC Java application that adds records through data forms to a database.
My app collects data, it also validates it and stores it. This is because the data is being sourced ...
1
vote
1answer
118 views
design pattern advice: graph -> computation
I have a domain model, persisted in a database, which represents a graph. A graph consists of nodes (e.g. NodeTypeA, NodeTypeB) which are connected via branches. The two generic elements (nodes and ...
3
votes
1answer
287 views
Domain Models (PHP)
I have been programming in PHP for several years and have, in the past, adopted methods of my own to handle data within my applications.
I have built my own MVC, in the past, and have a reasonable ...
1
vote
2answers
330 views
Relationship between SOA and OOA
Thomas Erl defines SOA as follows in his site:
Service-oriented computing represents a new generation distributed
computing platform. As such, it encompasses many things, including its
own ...
2
votes
1answer
341 views
Design patterns and multiple programming languages
I am referring here to the design patterns found in the GOF book. First, how I see it, there are a few peculiarities to design pattern and knowing multiple languages, for example in Java you really ...
2
votes
5answers
332 views
software architecture (OO design) refresher course [closed]
I am lead developer and team lead in a small RAD team. Deadlines are tight and we have to release often, which we do, and this is what keep the business happy.
While we (the development team) are ...
9
votes
7answers
729 views
Interfaces on an abstract class
My coworker and I have different opinions on the relationship between base classes and interfaces. I'm of the belief that a class should not implement an interface unless that class can be used when ...
0
votes
5answers
724 views
Inheritance vs composition in this example
I'm wondering about the differences between inheritance and composition examined with concrete code relevant arguments.
In particular my example was
Inheritance:
class Do:
def do(self):
...
4
votes
1answer
154 views
What is a “behavior rich object” and why would it be advantageous?
I am referring to the article Mocks aren't Stubs by Martin Fowler. When naming cases when he think "mockist" TDD will be advantageous, he said
It's particularly worth trying if you are having ...
5
votes
4answers
533 views
Can a loosely typed language be considered true object oriented?
Can a loosely typed programming language like PHP be really considered object oriented?
I mean, the methods don't have returning types and method parameters has no declared type either.
Doesn't ...
4
votes
1answer
262 views
Whats a better way of designing this class
Currently I have some code like this:
OntologyGenerator generator = new OntologyGenerator();
generator.AddOntologyHeader("Testing");
generator.AddClassDeclaration(owlBuilder);
...
5
votes
3answers
449 views
Is it a better practice pre-initialize attributes in a class, or to add them along the way?
I'm sorry if this is a ABSOLUTELY sophomoric question, but I'm curious what the best practices are out there, and I can't seem to find a good answer on Google.
In Python, I usually use an empty class ...
