Inheritance is a way to reuse code of existing objects, or to establish a subtype from an existing object, or both, depending upon programming language support.
2
votes
3answers
149 views
OOP concept: is it possible to update the class of an instantiated object?
I am trying to write a simple program that should allow a user to save and display sets of heterogeneous, but somehow related data. For clarity sake, I will use a representative example of vehicles. ...
-5
votes
0answers
66 views
Virtual function in C++ [closed]
I have some doubts regarding inheritance in C++ language.
What is a virtual function?
Why does one need to define virtual functions in a class?
If I define/declare a virtual function in a base ...
2
votes
4answers
138 views
Initializing derived classes in the same way
I have a class Base that has several children, say A, B, C. For testing purposes I'd like to mock those derived classes by deriving from them. So MockA derives from A, MockB derives from B and so on.
...
8
votes
1answer
180 views
Why is the use of constructors discouraged when creating prototypes?
Quick background: In JavaScript, the constructor function for each object type has a prototype property. The prototype refers to an object that each constructed object uses as the next step up in its ...
27
votes
13answers
2k views
Multiple Interfaces in Java - Good or bad
I'm coming out of an interview just now and the interviewer asked me if a Java interface can "extend" more than one interfaces. I was thinking multiple inheritance is disallowed in java so got that ...
7
votes
6answers
894 views
Why are constructors not inherited?
I am confused as to what the problems could be if a constructor was inherited from a base class. Cpp Primer Plus says,
Constructors are different from other class methods in that they
create ...
1
vote
2answers
262 views
What principle of OOAD is this pattern breaking?
I'm trying to make a case for not putting the structure in the parent BaseModule class I've shown below. I'm more for a Strategy Pattern, and minimizing inheritance in favor of has-a relationships, ...
7
votes
2answers
266 views
How do I avoid writing lots of pass-through functions in a wrapper?
I have a class, which wraps another class of a common base type. Because the base type interface is quite large this involves writing a lot of pass-through functions. I am looking for a way to avoid ...
1
vote
0answers
86 views
Inheritance and constricted referencing
Let's say I have BaseA and BaseB classes. BaseB can have to several references of BaseA instances. Now, we have two other classes, DerivedA and DerivedB that respectively inherit from BaseA and BaseB.
...
1
vote
1answer
130 views
Class table inheritance… To 'type' or not to 'type'
I currently have a database that uses Class table inheritance model. Three different tables inherit from this table. The child tables have all a FK to the parent table and the fields are properly ...
3
votes
2answers
235 views
Tricky compareTo, inheritance, easy to extend - Java
Let's say we have 4 classes A, B, C, D where: A is a superclass of both B and C and C is a superclass of D. I suppose, in a diagram, it should look like this:
A
/ \
B C
\
D
...
4
votes
2answers
290 views
Why Java does not support private/protected inheritance like C++? [closed]
While inheriting a class in C++, user can specify the access specifier like,
class Base
{
public int mem1;
protected in mem2;
};
class Derived1 : **private** Base
{
// mem1 will be ...
4
votes
5answers
559 views
How often is Inheritance used?
I admit that I am a junior developer, and so far I've only built simple web applications in ASP.NET MVC. But I've never had to use the inheritance aspect of Object Oriented Programming in my own ...
19
votes
7answers
705 views
Should I test inherited methods?
Suppose I have a class Manager derived from a base class Employee, and that Employee has a method getEmail() that is inherited by Manager. Should I test that the behaviour of a manager's getEmail() ...
0
votes
1answer
276 views
Code reuse via inheritance [duplicate]
I have a set of classes that are all dealing with some related tasks. These tasks do have different inputs and outputs. This causes it to become impossible to have the tasks done via shared code ...
2
votes
2answers
113 views
Template method within one class without subclasses or inheritance
I have an algorithm with mostly invariant parts that needs to be reused within one class so as to stay DRY.
Code duplication with repeating method structure
public void save(String key, int value) ...
5
votes
2answers
249 views
How does strengthening of pre conditions and weakening of post conditions violate Liskov Substitution principle?
I read that Liskov substitution principle is violated if :
Pre conditions are strengthened .
Post conditions are eased out.
But I don't get fully yet how these two points would violate Liskov ...
25
votes
5answers
1k views
Many small classes vs. logical (but) intricate inheritance
I'm wondering what is better in terms of good OOP desing, clean code, flexibility and avoiding code smells in the future. Image situation, where you have a lot of very similar objects you need to ...
6
votes
1answer
227 views
Declaring functions as final… except when it is me who does the deriving
I have a class in which I want to disallow other programmers from overriding one of it's methods, since it requires special knowledge of the inner workings of the class. Since I personally know how ...
1
vote
1answer
130 views
How to share common methods if objects have different roles?
If 2 classes have the following in common:
part of how their state is represented (both have a linear container)
multiple identical methods (identical code, not just signature)
But are not ...
3
votes
5answers
908 views
Why does Java allow to implement different interfaces, each containing a method with the same signature?
I recently found out that I can have two interfaces, one containing a method with the same signature as a method in the other interface. And I can have an interface or class that implements both of ...
6
votes
4answers
542 views
Looking for a real-world example illustrating that composition can be superior to inheritance
I watched a bunch of lectures on Clojure and functional programming by Rich Hickey as well as some of the SICP lectures, and I am sold on many concepts of functional programming. I incorporated some ...
2
votes
2answers
471 views
Alternative to “inheritance versus composition?” [duplicate]
Possible Duplicate:
Where does this concept of “favor composition over inheritance” come from?
I have colleagues at work who claim that "Inheritance is an anti-pattern" and want to use ...
4
votes
2answers
374 views
Naming methods that do the same thing but return different types
Let's assume that I'm extending a graphical file chooser class (JFileChooser).
This class has methods which display the file chooser dialog and return a status signature in the form of an int: ...
1
vote
2answers
293 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 ...
0
votes
0answers
56 views
Class hierarchy problem in this social network model
I'm trying to design a class system for a social network data model - basically a link/object system. Now I have roughly the following structure (simplified and only relevant methods shown)
class ...
0
votes
2answers
84 views
How do you handle objects that need custom behavior, and need to exist as an entity in the database?
For a simple example, assume your application sends out notifications to users when various events happen. So in the database I might have the following tables:
TABLE Event
EventId ...
7
votes
1answer
372 views
JavaScript objects and Crockford's The Good Parts
I've been thinking quite a bit about how to do OOP in JS, especially when it comes to encapsulation and inheritance, recently.
According to Crockford, classical is harmful because of new(), and both ...
2
votes
7answers
666 views
OO Software Architecture - base class that everything inherits from. Bad/good idea?
I am reviewing a proposed OO software architecture that looks like this:
Base
Foo
Something
Bar
SomethingElse
Where Base is a static class.
My immediate thought was that every object in any ...
0
votes
5answers
789 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):
...
-3
votes
2answers
351 views
Why don't inherited methods use child properties? (PHP)
I'm trying to get the code below to work in child classes. But it keeps failing because it is checking the basicDbClass rather than the child class.
For those complaining and voting my question down ...
2
votes
5answers
2k views
How to create a common interface for classes with different subsets of members
Don't know how to put it, But I'll try to be as clear as possible
I have a project in which I am creating lots of classes and those classes have some common properties and methods but those methods ...
3
votes
1answer
245 views
What is the best way to use inheritance with ORMs?
If I have a People table and those people can be at different addresses, and each address can have more than one person, thats a many-to-many relationship.
So, using ORMs like Entity Framework and ...
3
votes
7answers
591 views
Inheritance using non-abstract base class
This post is based on the question http://stackoverflow.com/questions/49002/prefer-composition-over-inheritance/11758048#comment15634305_11758048.
Some people said - check whether there is “is-a” ...
2
votes
1answer
346 views
Composition vs. Inheritance
Here's what is given:
public interface Request {}
// there are 20 subclasses of Request
public class CreateUserRequest implements Request {
@NotEmpty
public String userName;
}
// request ...
7
votes
9answers
943 views
What OO Design to use ( is there a Design Pattern )?
I have two objects that represent a 'Bar/Club' ( a place where you drink/socialise).
In one scenario I need the bar name, address, distance, slogon
In another scenario I need the bar name, address, ...
37
votes
11answers
4k views
Why is it good to split a program into multiple classes?
I'm still a student in high school (entering 10th grade), and I have yet to take an actual computer course in school. Everything I've done so far is through books. Those books have taught me concepts ...
2
votes
3answers
1k views
Can I use a child class variables in its parent class?
I am programming in Objective C, iOS. I create a Class A which is a parent class, and Class B inherits to Class A.
Now I have Class B variables which I also need to use in Class A. And also one ...
1
vote
2answers
522 views
Is it a good programming practice to have a class with several .h files?
I suppose the class have several different interfaces. Some it shows to some class, some it shows to other classes.
Are there any good reason for that?
One thing I can think of is with one .h per ...
3
votes
2answers
202 views
Does Parallel Inheritance Make for Good Code?
I'm writing a database interface in PHP and I have a base dbTables class, as well as a base dbTableFields class.
dbTables has a function, getFields(), that instantiates dbTableFields objects, each of ...
1
vote
2answers
119 views
Extend the API or use the same name as a class in the API?
I have been running into this problem more and more: I am not happy with the current API, and end up making my own class that does what I wish the API did; however, I don't extend the 'super class' as ...
4
votes
1answer
275 views
Any valid reason to Nest Master Pages in ASP.Net rather than Inherit?
Currently in a debate at work and I cannot fathom why someone would intentionally avoid Inheritance with Master Pages.
For reference here is the project setup:
BaseProject
...
3
votes
2answers
292 views
Derived Classes and namespaces
I am deriving a class, for use in my application, from a class provided by another group. Should the derived class be in the namespace for my application or the namespace of the parent class?
While ...
7
votes
6answers
959 views
Why is subclassing too much bad (and hence why should we use prototypes to do away with it)?
I was reading up on design patterns, and I read that the prototype design pattern does away with excessive subclassing.
Why is subclassing bad? What advantage would using a prototype bring about over ...
2
votes
1answer
1k views
Rails - to use STI or not…that is the question
Six months ago, I asked a question about modeling data for my app, and received some advice pointing me towards STI (see Rails data model - best practices question for the details).
I played around ...
7
votes
5answers
914 views
Interface and Inheritance: Best of both worlds?
I 'discovered' interfaces and I started to love them. The beauty of an interface is that it is a contract, and any object that fulfills that contract can be used wherever that interface is required.
...
20
votes
4answers
6k views
Why should I prefer composition over inheritance?
I always read that composition is to be preferred over inheritance. A blog post on unlike minds, for example, advocates using composition over inheritance, but I can't see how polymorphism is ...
5
votes
3answers
720 views
When calling a method should we use base.methodname and this.methodname?
In C#, with an inherited class set -- when calling a method should we use keywords 'base.methodname and this.methodname'... irrespective of whether it is a overridden method or not?
The code is ...
1
vote
2answers
1k views
Are super methods in JavaScript limited to functional inheritance, as per Crockford's book?
In Douglas Crockford's "JavaScript: The Good Parts", he walks through three types of inheritance: classical, prototypal, and functional. In the part on functional inheritance he writes:
"The ...
4
votes
2answers
297 views
Who decided on the terminology downcasting and upcasting?
As far as I know, the terminology comes from how the inheritance hierarchy is traditionally displayed, with the extending types at the bottom, and the parent types at the top.
This is a bit ...
