This is where the “compiler magic” happens… the interfaces are checked
internally - if the compiler can find a method where the receiver type matches
the parameter type, and it returns a value which is the receiver type, it can
use the + operator on it, if not it is a compiler error.
As others have pointed out I don’t think there aren't too many of these
internal interfaces needed, the operators and collection methods.
Still, if you want to change the language, then you could do something like
type PlusOperator interface {
Plus($) $
}
where $ always matches the receiver type defining the method. So for a type A
to satisfy PlusOperator it must have a Plus method that accepts an A and
returns an A.
You could also define this
type PlusOperator interface {
Plus(int) $
}
which would allow me to do A + n pretty easily. Although I’ve never been a fan
of operator overloading outside of math contexts.
Get a little hairier when the parameters and results are interface types
themselves, but still doable I think.
Just an idea… Not full blown generics but should allow type safe generic
collections with the proper internal interfaces defined.
> On Sep 9, 2018, at 1:52 PM, Jonathan Amsterdam <jbamster...@gmail.com> wrote:
>
>
>
> On Saturday, September 8, 2018 at 11:58:46 PM UTC-4, Robert Engels wrote:
> For the math operator, since Go already doesn’t do automatic numeric
> conversions, all of the operators are almost trivially implemented as
> methods, e.g. operator + is
>
> pseudo generic interface - not really required
>
> type PlusOperator<type A> interface {
> Plus(A) A
> }
>
> This generic interface does not capture the + operator. The spec says that
> the the operands and result of + are all the same type. Your interface is
> satisfied by any type B with a method Plus(A) A. Types A and B do not have to
> be the same.
>
>
>
> type MyStruct struct {
> }
> func (MyStruct) Plus(other MyStruct) MyStruct {
> …
> }
>
> but also
>
> type MyOtherStruct struct{}
> func (MyOtherStruct) Plus(other MyStruct) MyStruct {
> }
>
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