Questions tagged [abstract-class]
An abstract class is a class that cannot be instantiated. They are generally meant to be extended/subclasses and generally have "abstract methods" that must be implement by subclasses.
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Which methods should be put in an interface and which in abstract classes?
I have seen many frameworks and modules and their standard they follow is like this
UserInterface which have some predefined methods
AbstractUserClass which implements userInterface
Then ...
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observer class as instance
Sometimes I read in observer-pattern descriptions, to make the constructor of a observer base class protected so the class will be abstract. but by making the constructor public (if even one is ...
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Interface Dependencies or Abstract Classes
I have a decision to make and I am wondering what would be the better solution. I am refactoring an older application and intend to really get into the nuts and bolts of it.
There are 8 report types ...
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Building a database class in PHP
I wonder if I should write a database class for my application, and if so, how to accomplish it?
Over there on SO, a guy mentioned it should be written as an abstract class. However, I can't ...
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Refactoring an existing abstract class and its parameters
I have an abstract class A which declares an abstract method doStuff. Currently there are many classes that inherit from A and implement doStuff.
The class' instances are initialized at run-time ...
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Is there any difference between interfaces and abstract classes that have abstract methods only?
Let's say we have an abstract class and let this class has only abstract methods. Is this abstract class different from an interface that has same methods only?
What I am looking to know is if there ...
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In C++ why and how are virtual functions slower?
Can anyone explain in detail, how exactly the virtual table works and what pointers are associated when virtual functions are called.
If they are actually slower, can you show the time that the ...
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Questions about Polymorphism
So I understand the importance of Polymorphism, including how vital it is. But something I don't quite understand is what about the Constructor and any inherited Class the initial Base Class may have....
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Should I implement an interface directly or have the superclass do it?
Is there a difference between
public class A extends AbstractB implements C
{...}
versus...
public class A extends AbstractB
{...}
abstract class AbstractB implements C
{...}
I understand that in ...
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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 ...
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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. ...
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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, ...
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Help to understand the abstract factory pattern
I'm learning the 23 design patterns of the GoF.
I think I've found a way to understand and simplify how the Abstract Factory works but I would like to know if this is a correct assumption or if I am ...
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Abstract class + Inheritance vs Interface
Hello fellow programmers,
I am reading a book on C# and the author is comparing Abstract classes and Interfaces. He claims that if you have the following "abstract class:"
abstract class ...
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Is there a different usage rationale for abstract classes/interfaces in C++ and Java
According to Herb Sutter one should prefer abstract interfaces (all pure virtual functions) to abstract classes in C++ to decouple the implementation as far as possible. While I personally find this ...
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Switching from abstract class to interface
I have an abstract class which has all abstract methods except one which constructs objects of the subclasses. Now my mentor asked me to move this abstract class to an interface.
Having an interface ...
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What are the roles of singletons, abstract classes and interfaces?
I am studying OOP in C++ and, even though I am aware of the definitions of these 3 concepts, I cannot really realize when or how to use it.
Let's use this class for the example:
class Person{
...
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Should all public methods in an abstract class be marked virtual?
I recently had to update an abstract base class on some OSS that I was using so that it was more testable by making them virtual (I could not use an interface as it combined two). This got me thinking ...
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Abstract base classes and copy construction, rules of thumb
Often times it's a good idea to have an abstract base class to isolate the interface of the object.
The problem is that copy construction, IMHO, is pretty much broken by default in C++, with copy ...
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Abstract methods vs instance variables for reusable objects
I have quite a bit of Java code that I'm re-working to be re-used. The problem is that there are many pieces that are project specific so there are ends up being a higher level of coupling between ...
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What other reasons are there to write interfaces rather than abstract classes? [duplicate]
Possible Duplicate:
When to use abstract classes instead of interfaces and extension methods in C#?
When I read and looked at codes using Abstract classes, I was able to justify it because it ...
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What is the best design decision approach?
I have two classes (named MyFoo1 and MyFoo2) that share some common functionality. So far, it does not seem like I need any polymorphic inheritance but, at this point, I am considering the following ...
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Abstract exception super type
If throwing System.Exception is considered so bad, why wasn't Exception made abstract in the first place?
That way, it would not be possible to call:
throw new Exception("Error occurred.");
This ...
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Designing Subclasses for an abstract base class in C++
I'm doing a small assignment in C++ where I have to use concepts like virtual functions and inheritance in a domain of my choice. I'm implementing the prototype for a package manager in Linux.
I have ...
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Can I consider interface methods as abstract methods?
I was thinking about that, and I had some doubts.
When I declare an interface, for example:
public interface MyInterface
{
public void method1();
public void method2();
}
Could these ...
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Why should I declare a class as an abstract class?
I know the syntax, rules applied to abstract class and I want know usage of an abstract class
Abstract class can not be instantiated directly but can be extended by other class
What is the ...
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When to use abstract classes instead of interfaces with extension methods in C#?
"Abstract class" and "interface" are similar concepts, with interface being the more abstract of the two. One differentiating factor is that abstract classes provide method implementations for derived ...
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