61
votes
Accepted
What is the earliest use of the "this" keyword in any programming language?
Simula 67 is generally considered the first object-oriented language and predates Smalltalk by a number of years.
It also used the this keyword for the same ...
- 1,833
24
votes
Accepted
Automatic Downcasting by Inferring the Type
Upcasts always succeed.
Downcasts can result in a runtime error, when the object runtime type is not a subtype of the type used in the cast.
Since the second is a dangerous operation, most typed ...
- 14.4k
10
votes
Accepted
What is the origin of dot notation?
In [1] (authored by one of the co-creators of Simula), there is a suggestion that Simula 67 may have been the first to use this dot notation. Given that Simula is widely credited for being the first ...
- 2,012
9
votes
Accepted
What is the difference between Abstract Data Types and objects?
Google brought up a similar question with an answer that I think is very good. I've quoted it below.
There's another distinction lurking here that is explained in the Cook
essay I linked.
...
- 321
7
votes
What would "sum types with functions" look like in OOP?
The key to remember is that there's a sort of dualism between functional sum types, and OOP implementations of a superclass or interface:
Sum types require the variants for a type to be specified up ...
- 29.7k
5
votes
Accepted
The C3 linearization algorithm for method resolution in multiple inheritance OO languages: Looking for a justification for some implementation detail
Without the last list:
merge(<B,D,O>, <C,F,O>, <D,O>) =
<B,D,C,F,O>
With the last list:
...
- 14.4k
4
votes
Identity of object in OOP
Depending on the programming language, some or all objects might have reference semantics. What this means is that when you assign the object to a variable or pass it to a method, it's still the same ...
- 1,866
4
votes
What would "sum types with functions" look like in OOP?
Hm, I don't have the points to comment, but are you sure you mean that?
Classes already are a sort of sum type: polymorphism means that a variable declared to refer to something of type "A" could ...
- 141
4
votes
Accepted
Which object-oriented programming language is the closest to the untyped sigma-calculus?
JavaScript looks perfectly like untyped sigma calculus.
It supports first-class citizens, described in paper concepts in terms of prototypes, closures, clone (called split), (dynamic) method override,...
- 9,425
4
votes
What is the difference between Abstract Data Types and objects?
If you look at the ADT proponents, they consider an ADT to be what OOP would call a class (internal, private state; a limited set of operations allowed), but no relation between classes (no ...
- 13.9k
4
votes
Is it possible to implement dependent types by any object oriented language supporting inheritance and classes?
So, things like this are possible, but the usefulness varies depending on your system.
First, you can absolutely model object oriented programming in a functional, formal setting. System F-sub is the ...
- 29.7k
4
votes
Accepted
Was multiple inheritance ever implemented by adding redundant data members?
It does not matter how you implement multiple inheritance, the inherent issues coming from that still apply.
If $C$ is a class, and $D$ a derived class (subclass), and $d:D$ we can write ...
- 14.4k
3
votes
How to implement polymorphism in a turing complete environment?
So, first, a question. Are you using dynamic or static dispatch? i.e. if Circle and Shape provide implementations of the same ...
- 29.7k
3
votes
Automatic Downcasting by Inferring the Type
It's a matter of where do you want to draw the line. You can design a language that will detect validity of implicit downcast:
...
- 213
3
votes
Automatic Downcasting by Inferring the Type
Usually downcasting is what you do when the statically known knowledge the compiler has about the type of something is less specific than what you know (or at least hope).
In situations like your ...
- 1,674
3
votes
Are synchronous message sends a subset of async. ones?
There are several possible semantics for asynchronous message passing, so there isn't a single answer to this question. It depends how the scheduler works.
From a theoretical perspective, the ...
3
votes
What is the difference between Abstract Data Types and objects?
I always understood it this way:
An ADT is an interface: it is just a collection of methods, their type-signatures, possibly with pre-and-post conditions.
A class can implement one or more ADTs, by ...
- 29.7k
3
votes
Accepted
What is the difference between the friend class and inheritance consept in C++?
To declare a class (or a function) a friend allows the friend to access private members [the naming in C++ is not my fault!] (data or function) directly. They aren'...
- 13.9k
3
votes
Does the concept of subtype require dynamic method binding?
No. It doesn't even require a notion of "method" at all. Even if you have objects and methods, it doesn't necessarily require a notion of dynamic dispatch. Indeed, dynamic dispatch is only relevant if ...
3
votes
Which is a type of objects in mainstream OO languages: a class, an interface, an abstract class, a metaclass?
Unfortunately I don't have a copy of TAPL with me, so I can't figure out exactly what the author intends. But there is a point we should make, that types are something which classifies terms or values,...
- 326
3
votes
What subfields in computer sciences may one study without learning Object Oriented Programming?
Depending on where you study, you might be able to get a CS degree without Object Oriented Programming, but the chances are slim. Most degrees would require you to take some programming courses using ...
- 28.3k
3
votes
Are objects appropriate for modeling the real world?
Object-oriented programming languages are designed to support programming. Whether they "properly" model the real world is beside the point and not the primary goal. So, when you ask "...
D.W.♦
- 156k
3
votes
Why we dont use dot operator with int or any other datatype
There are languages where "everything is an object". The archetype is Smalltalk, although Smalltalk does not think in terms of "method calls", but rather "messages".
In ...
- 21.6k
2
votes
What does Harper mean by "class"?
This is a very generic, informal definition of the concept of classes which is commonly implemented in programming languages. I can't think of a programming language that uses the term “class” in a ...
2
votes
What does Harper mean by "class"?
The term class here has absolutely nothing to do with OOP classes. Rather, a class determines which possibility in a C union an object takes.
For example, one ...
- 275k
2
votes
Definition of the state of an object in OOP
The term ‘state’ may be used in various senses, which may not even all be susceptible of a precise definition. It was therefore important that you include a definition in your paper, to make quite ...
- 382
2
votes
how does an object find the reference to its instance variables
Since the class is fixed in advance in C++-style languages, the offset to a5 or a450 is known in advance, in compile time. Each ...
- 275k
2
votes
Accepted
Term for members of a class that are not inherited
Just a member variable. If you want to specify that it is not inherited, I suppose you could call it 'noninherited member variable'. Wiktionary lists this as a term in computing.
- 248
2
votes
Accepted
What's the difference between subtyping and inheritance?
See the following discussions in other stack exchange groups.
See discussion in https://stackoverflow.com/questions/23592131/what-is-the-difference-between-subtyping-and-inheritance-in-oo-programming
...
- 479
Only top scored, non community-wiki answers of a minimum length are eligible