In OOP (Object Oriented Programming), a base class that cannot be instantiated because some of its declared methods lack a definition, which is intended to be provided by derived classes. The term may have more specific or slightly different meaning according to the particular computer language involved.
Questions tagged [abstract-base-class]
109 questions
1
vote
1 answer
Pure virtual function in abstract class with return type of base/derived type
I wish to make each derived class of a base class to implement a function (in this case the postfix operator) which has the derived class' type as return type, as this:
class A {
virtual A operator++(int) =0;
}
class B : public A {
B…
Parham
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1
vote
3 answers
C# Xml-Serialization of abstract base type into derived type - which TypeName property definition wins?
My scenario:
I have an object that I have defined with properties that are decorated with XmlElement tags and that have types that I have defined, some of which are typed as abstract that get set to respective derived types. I want to serialize this…
null
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1
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4 answers
Pointer to base class lost in while loop, causing segfault. C++
This code uses a while loop to get user input and execute the appropriate command - I've reduced it to 2 commands for sake of brevity.
The Oblock object is created correctly (command "O"), as is the pointer to the base class. It appears that the…
user3566909
1
vote
1 answer
Defining multiple derived Interface Members
I hope you can help me with the following problem.
I am trying to create a flexible system of interfaces and hit a problem.
This is the relevant code:
// Interface 1
// this: virtual f_a
// -> abstract
struct I_A abstract
{
virtual void…
Beta Carotin
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- 1
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1
vote
3 answers
Unit testing passing arguments to base constructor
I have the following code:
using System;
using NUnit.Framework;
using Rhino.Mocks;
public class A
{
}
public class B
{
}
public interface IStatementExecutor
…
drogon
- 1,785
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0
votes
1 answer
Passing a web control reference to a User Control base class
I created several user controls - most containing a single web control (text box, drop down, radio button etc) - along with one or more validation controls. The point being to combine control and validation in a single user control.
I created a…
mearle
- 3
- 2
0
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5 answers
STL List - Datatype as a pointer object
I'm having a problem using inheritance and the STL list library...
Say, I have an abstract base class with two derived classes (where all comparison operators are defined). The list is declared as
list items;
I'm inserting a derived…
Joseph Sutton
- 97
- 8
0
votes
1 answer
Can you force derived class from a bass class to define specific member variables in python?
If I have a class say:
class BaseClassOnly():
def __init__(self):
self._foo = None
def do_stuff(self):
print("doing stuff with foo" + self._foo)
I want to force all classes derived from BaseClassOnly to provide a value for…
user21113865
- 99
- 7
0
votes
1 answer
Inheriting from type and typing.Mapping: "TypeError: descriptor '__subclasses__' of 'type' object needs an argument"
I am trying to define a class that is supposed to simultaneously do two things:
serve as the metaclass for a dataclass
act like a mapping
i.e., it will need to be derived from both type and typing.Mapping.
Defining such a class itself works, but I…
0
votes
0 answers
What is the point of passing in params to an abstract base class in this manner?
I was trying to understand how the backtesting.py module is written and came across this code.
class Strategy(metaclass=ABCMeta):
"""
A trading strategy base class. Extend this class and
override methods
…
Abhishek Banerjee
- 27
- 5
0
votes
1 answer
how can vb.net make inherit class with selected variable from base calss
I need to make an inherited class from a base class with a selected variable.
for example,
if the base class have 3 variable name, age, marks
but inherit class must have name and marks only
how can we do it
Visula Kavinda
- 3
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0
votes
1 answer
Why default assignment operator is not called from assignment-from-base-class operator?
Implementing a derived class from abstract base class with assignment operator by using dynamic cast in base-to-derived assignment operator, I'd like to call derived-to-derived assignment operator. This works.
#include
using namespace…
Nick
- 970
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0
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1 answer
Return Base class shared pointer using derived class C++
I have a an interface:
/*base.hpp */
class Base {
protected:
Base() = default;
public:
Base(Base const &) = delete;
Base &operator=(Base const &) = delete;
Base(Base &&) = delete;
Base &operator=(Base &&) = delete;
…
Incredible
- 3,495
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0
votes
1 answer
Use subclasses of abstract outer class in nested class
I want to use all subclasses of an abstract class in the nested config class of a pydantic class like this:
def custom_json_loads(classes, ....):
##use classes here for json parsing
class Outer(BaseModel, abc.ABC):
name = "test"
class…
Tabea
- 39
- 1
- 7
0
votes
2 answers
Abstract base class or typing.Protocol for supporting __str__
Is there a builtin ABC for enforcing __str__ to be implemented in subclasses? Or a typing protocol?
I want a function that only accepts classes with __str__ __hash__ and __eq__. I've found Hashable but not Stringable
Greedo
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