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Questions tagged [subclass]

A subclass is a class that derives or inherits from a parent (or super) class. Subclassing is used extensively in object-oriented programming (OOP).

A subclass is any class that inherits from a parent (or super/base) class. Depending on the language, a subclass will have a subset of the attributes and methods of the (parent/base) class from which it inherits. As a result, it is important to always tag a question with the language being used when tagging it with this tag

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How can I change the default value of an inherited dependency property?

How can I change the default value for an inherited dependency property? In our case, we've created a subclass of Control which by default has its Focusable set to 'true'. We want our subclass to have the default of 'false'. What we've been doing…
Mark A. Donohoe
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Python: Can a subclass of float take extra arguments in its constructor?

In Python 3.4, I'd like to create a subclass of float -- something that can be used in math and boolean operations like a float, but has other custom functionality and can receive an argument at initialization that controls that functionality.…
Shimon Rura
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In what ways are subtypes different from subclasses in usage?

A subtype is established when a class is linked by means of extending or implementing. Subtypes are also used for generics. How can I differentiate subtyping from subclasses?
Oh Chin Boon
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Why can't I subclass datetime.date?

Why doesn't the following work (Python 2.5.2)? >>> import datetime >>> class D(datetime.date): def __init__(self, year): datetime.date.__init__(self, year, 1, 1) >>> D(2008) Traceback (most recent call last): File "",…
Arkady
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How to add constraints on inherited properties in a grails domain sub-class

Here's what I'd like to do: class A { String string static constraints = { string(maxSize:100) } } class B extends A { static constraints = { string(url:true) } } So class A should have some constraints and B should have the same…
Jörg Brenninkmeyer
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Subclassing builtin types in Python 2 and Python 3

When subclassing builtin types, I noticed a rather important difference between Python 2 and Python 3 in the return type of the methods of the built-in types. The following code illustrates this for sets: class MySet(set): pass s1 = MySet([1,…
khinsen
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What's the usage of a virtual subclass?

class AnimalMeta(type): def __instancecheck__(cls, instance): return cls.__subclasscheck__(type(instance)) def __subclasscheck__(cls, sub): return (hasattr(sub, 'eat') and callable(sub.eat) and hasattr(sub,…
weiwang
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Subclassing Numpy Array - Propagate Attributes

I would like to know how custom attributes of numpy arrays can be propagated, even when the array passes through functions like np.fromfunction. For example, my class ExampleTensor defines an attribute attr that is set to 1 on default. import numpy…
Overholt
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What's the difference betwen a UserControl and a ContentControl?

According to all of the documentation, when you're creating a non-lookless control, you're supposed to subclass UserControl. However, UserControl is a simple subclass of ContentControl but it doesn't appear to add anything to it, interface-wise. …
Mark A. Donohoe
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How to create an immutable dictionary in python?

I want to subclass dict in python such that all the dictionaries of the sub-class are immutable. I don't understand how does __hash__ affects the immutability, since in my understanding it just signifies the equality or non-equality of objects ! So,…
Yugal Jindle
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Understanding subclassing of JSONEncoder

I am trying to subclass json.JSONEncoder such that named tuples (defined using the new Python 3.6+ syntax, but it probably still applies to the output of collections.namedtuple) are serialised to JSON objects, where the tuple fields correspond to…
Xophmeister
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Should I subclass the NSMutableArray class

I have an NSMutableArray object that I want to add custom methods to. I tried subclassing NSMutableArray but then I get an error saying "method only defined for abstract class" when trying to get the number of objects with the count method. Why is…
node ninja
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Overriding a parent class's methods

Something that I see people doing all the time is: class Man(object): def say_hi(self): print('Hello, World.') class ExcitingMan(Man): def say_hi(self): print('Wow!') super(ExcitingMan, self).say_hi() # Calling the…
orokusaki
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Override a "private" method in Python

Consider a class with a "private" method such as: class Foo(object): def __init__(self): self.__method() def __method(self): print('42') When I try to subclass Foo and override method __method, it can be seen that…
Ernest A
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How to handle NestJS Dependency Injection when extending a class for a service?

I am trying to provide a different service based on a value from my ConfigService. The problem I am running into is that the mongoose model that gets injected does not return any values when executing query methods such as findOne() (result is…
cameronliam
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