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
3
votes
1 answer
Getting all registered subclasses of an ABCMeta
I have a directory structure similar to the following:
.
├── main.py
├── model.py
└── models
├── __init__.py
├── model_a.py
└── model_b.py
model.py contains an Abstract Base Class:
from abc import ABCMeta, abstractmethod
class…
BioGeek
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3
votes
1 answer
@staticmethod return value
In Python 3.6, I was trying to define a property in an AbstractBaseClass; my first try was something like this (later I discovered I can omit @staticmethod):
class AnAbstractClass(ABC):
@property
@staticmethod
@abstractmethod
def…
entropiae
- 85
- 1
- 6
3
votes
1 answer
C++ "Pure virtual method called" with use of abstract baseclass
I am using a abstract baseclass with only pure virtual methods, to have a interface behavior (yes, I am coming from Java) in C++.
As far as I did my research this seems to be the way to go.
I have to abstract base classes, GraphReader and…
nurgan
- 53
- 8
2
votes
1 answer
Error Related to FK in One-to-Many Relationship
I am using EF 5 Beta 2 Code-First. I have created an edmx file which has 2 entities among others named Brand and Vehicle.
One Brand can have zero or more (many) Vehicles and every Vehicle should have a Brand (required).
Vehicle has a foreign key…
Kamran
- 782
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- 35
2
votes
1 answer
Cloning Derived classes from Base classes
I have an Event base class with a DerivedEvent. I also have BaseA with DerivedA and BaseB with DerivedB classes. The B classes have A objects in them. the A objects update a queue of event pointers: std::queue> from the B…
road_to_quantdom
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2
votes
1 answer
Django field clash with multiple abstract base clases
I am trying to define entity architecture that, if simplified, can be expressed like this:
class M(models.Model):
field_m = models.CharField(max_length=255)
class Meta:
abstract = True
class A(M):
field_a_1 =…
Arsen Simonean
- 362
- 2
- 17
2
votes
0 answers
C++: Enforce Singleton on Subclasses of ABC
Whithin an already exisitng Simulation framework I am trying to implement the state pattern on already exising abstract base classes of models. As the model class is only an ABC, so should be the states.
I am searching for a way to enforce the…
R.Tazke
- 21
- 1
2
votes
2 answers
I don't understand why it is wrong to test for possible interfaces in a base class
I have an abstract base class that will be used in hundreds of derived classes, including an additional abstract class.
There are at least 2 properties (let's call them Purpose and Description, both strings) that will be added to many (but not all)…
DanK
- 59
- 7
2
votes
1 answer
C++ implementing abstract classes
I am trying to write a derived class called TerminalPlayer that inheritances a class Player given the declaration of virtual const Card playCard(const Card opponentCard) = 0; how would you implement the inherited playCard in the abstract class and…
TheWinterSnow
- 175
- 11
2
votes
3 answers
C++: How to create an abstract base class if class has no member functions?
I have an abstract base class, which serves the purpose of allowing an array of pointers to a base class to be created. (Useful for 'many things'...)
My abstract base class contains no member functions. Therefore there are no pure virtual methods,…
FreelanceConsultant
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2
votes
1 answer
Database structure to handle similar/same object at varying business levels
Scenario
A well-known taco establishment wants to build a Django app with models Combo, ComboItem, Ingredient, and Order.
Headquarters wants to create various combos with included items and layout the original item ingredients and price.
Each…
Ryan Allen
- 5,414
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2
votes
2 answers
Test that Python code only uses ABC methods
Let's say I have a function that is documented to take a collections.Sequence ABC. How do I test the code within this function against the ABC interface? Can I write a unit test (or tests) confirming that my code only calls methods defined by this…
detly
- 29,332
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2
votes
1 answer
Why is __slots__ behaving differently in Python 2 and 3 when inheriting from an abstract base class
I created the following class to store changeable points on a plane in a memory-efficient manner - I need a mutable equivalent of namedtuple('Point', 'x y'). Since instance dictionaries are big, I thought I'd go for __slots__:
from collections…
Antti Haapala -- Слава Україні
- 129,958
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1
vote
2 answers
How do you initialize protected members of an abstract base class?
Perhaps I am worrying over nothing. I desire for data members to closely follow the RAII idiom. How can I initialise a protected pointer member in an abstract base class to null?
I know it should be null, but wouldn't it be nicer to ensure that is…
John
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1
vote
1 answer
Python: How to annotate a variable number of iterable attributes?
I have a class family for which I need to be able to iterate through attributes of type: Metric.
The family consists of an abstract base class parent and child classes. The child classes will all have varying number of class attributes of type…
Archie
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