Re: operator overloading

From:
Patricia Shanahan <pats@acm.org>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 27 May 2008 07:42:16 -0700
Message-ID:
<g1h6kb$rq7$1@ihnp4.ucsd.edu>
Tom Anderson wrote:

On Mon, 26 May 2008, Patricia Shanahan wrote:

Wojtek wrote:

Arne VajhHj wrote :

Operators only make the code more readable for classic arithmetic.


Which is my point.


Maybe this subthread suggests a solution. Define, for example, an
interface Addable<T> with

T additionOperation(T o);

as its only method.


Analogising to multiplication, this is going to make it impossible to
write my Matrix class which can be multiplied any of a double, a Vector,
or another Matrix, because you can't implement multiple instances of a
generic interface. Well, you could, but you'd have to do an instanceof
switch inside additionOperation, or implement some kind of ugly bounce
dispatch.

Anyway, i'm not happy with this solution, although i appreciate and
strongly agree with its intent.


Good point. How about this modification?

Addable, Multipliable, etc. become marker interfaces. Suppose a is a
reference to Multipliable or a type implementing Multipliable. Then the
compiler would process a+b as though it were a.multiplicationOperation(b).

You would make your Matrix class implement Multipliable, and provide
overloaded multiplicationOperation methods for formal parameter types
double, Vector, and Matrix.

Patricia

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