define polymorphism

[E. Robert Tisdale]

polymorph just means "many form(s)".
The definition in plain English

http://www.bartleby.com/61/66/P0426600.html

and narrower definitions in the context of computer programming

http://en.wikipedia.org/wiki/Polymorphism

http://wombat.doc.ic.ac.uk/foldoc/foldoc.cgi?query=polymorphism&action=Search

don't really help us understand what polymorphism means
in the context of the C++ computer programming language.

Simple operator overloading could be polymorphism.
Generic programming with templates could be polymorphism.
Or polymorphism may be restricted specifically
to run-time (dynamic binding) of a function call to it's implementation
(virtual functions).

[EventHelix.com]

Re: define polymorphism

In general usage of the term, it refers to inheritance with runtime
binding.

The Liskov Substitution Principle would be a good explaination of
polymorphism:

http://www.eventhelix.com/RealtimeMantra/Object_Oriented/liskov_substitution_principle.htm

Deepa
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EventStudio 2.5 - Generate Sequence Diagrams from plain text input

[Rolf Magnus]

Re: define polymorphism

E. Robert Tisdale wrote:
[color=blue]
> polymorph just means "many form(s)".
> The definition in plain English
>
> http://www.bartleby.com/61/66/P0426600.html
>
> and narrower definitions in the context of computer programming
>
> http://en.wikipedia.org/wiki/Polymorphism
>[/color]
http://wombat.doc.ic.ac.uk/foldoc/fo...&action=Search[color=blue]
>
> don't really help us understand what polymorphism means
> in the context of the C++ computer programming language.
>
> Simple operator overloading could be polymorphism.[/color]

That's not considered to be polymorphism.
[color=blue]
> Generic programming with templates could be polymorphism.[/color]

That is sometimes called "compile-time polymorphism".
[color=blue]
> Or polymorphism may be restricted specifically
> to run-time (dynamic binding) of a function call to it's implementation
> (virtual functions).[/color]

This is what is usually meant by the term "polymorphi sm".

[Dave O'Hearn]

Re: define polymorphism

E. Robert Tisdale wrote:[color=blue]
> polymorph just means "many form(s)".
> The definition in plain English
> [url]
> and narrower definitions in the context of computer programming
> [urls]
> don't really help us understand what polymorphism means
> in the context of the C++ computer programming language.
>
> Simple operator overloading could be polymorphism.
> Generic programming with templates could be polymorphism.
> Or polymorphism may be restricted specifically
> to run-time (dynamic binding) of a function call to it's
> implementation (virtual functions).[/color]

I liked the wiki's description. It would put overloading as a form of
ad-hoc polymorphism, templates as parametric polymorphism, and virtual
functions as subtyping polymorphism.

I have heard templates referred to as "parametric polymorphism" in a
lot of places. Stroustrup does it on page 347 of TC++PL, and Google
gives a lot of matches for (templates "parametric polymorphism"). So
that seems already to be accepted.

The wiki's terminology of "ad hoc polymorphism" for overloading is
something I had never heard before, though. It doesn't really feel like
polymorphism to me. I usually consider overloading to be syntactic
sugar, if very useful syntactic sugar.

--
Dave O'Hearn