PRE-PROPOSAL: Simple operator overloading. (original) (raw)

rssh at gradsoft.com.ua rssh at gradsoft.com.ua
Thu Mar 26 03:02:52 PDT 2009

interface Addable<R, T> { R add(T val); } class BigInteger implements Addable<BigInteger, BigInteger>, Addable<BigDecimal, BigDecimal> { ... } class BigDecimal implements Addable<BigDecimal, BigInteger>, Addable<BigDecimal, BigDecimal> { ... } I admit that doesn't look too elegant anymore, but I think it addresses the issue. Do you see any other problems there that I've overlooked? Yes, this can work.

Ohh, we need relief generics for this. Now see: http://www.angelikalanger.com/GenericsFAQ/FAQSections/TypeParameters.html#FAQ104

Cheers, Vil.

Sent from my iPod On 26 Mar 2009, at 01:08, Daniel Cheng <j16sdiz at gmail.com> wrote:

On Wed, Mar 25, 2009 at 8:03 PM, Vilya Harvey <vilya.harvey at gmail.com> wrote: I would love to see this, but I'd prefer it to be based on special interfaces rather than annotations. This would adhere to the principle, mentioned on this list a few times, that annotations shouldn't modify the results of the compiler.

For example, if you implement the Addable (say) interface then your class can be used the '+' operator; or the Subtractable interface for We can't specify the return type if we use an interface. We may want to do something like this: BigInteger + BigInteger = BigInteger BigInteger + BigDecimal = BigDecimal BigDecimal + BigInteger = BigDecimal BigDecimal + BigDecimal = BigDecimal There is no way to implement this using interface. the '-' operator. I'd imagine you would also want some grouping interfaces, to reduce the number of interface declarations required when overloading multiple operators (e.g. interface Artihmetic extends Addable, Subtractable etc.). Whatever form it takes though, it would be great to have this capability in Java! Vil.

2009/3/25 <rssh at gradsoft.com.ua>: Permanent URL: http://docs.google.com/Doc?id=dhhvggr818djp85shk Probably too big, but anyway. As I remember, alternative proposal (made [] and []= syntax sugar on well-known interfaces, as with for-each loop) still not submitted. If anybody want submit such proposal, then it is possible to reuse JLS-changed for 15.26.1 from there.

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