Purity, @safety, etc., in generic code

[deadalnix]

On Thursday, 21 February 2013 at 14:17:16 UTC, Steven 
Schveighoffer wrote:
>>>> Explain me how the hell you overload on implicit parameter 
>>>> types ?
>>>
>>> A method is simply a function that takes a hidden parameter 
>>> of an object or struct.
>>>
>>> Really, a method with a signature Obj.foo() is a function 
>>> with a signature foo(Obj this)
>>>
>>> A const method Obj.foo() const is a function with a signature 
>>> foo(const(Obj) this)
>>>
>>> So it's equivalent to saying you can overload:
>>>
>>> foo(int *x)
>>> foo(const(int) *x)
>>>
>>> To disallow this would be unnecessarily restrictive.
>>>
>>
>> That is called avoiding the question.
>
> I guess it's called not understanding the question?
>

The question is how do you overload function on the hidden 
parameter. The answer, we both know it is that you can't.

You say that this is is just like a regular function but this is 
in fact very different. You have virtual dispatch and overriding 
capabilities in case of methods. And combined with the capability 
of overload on const, this create a whole new set of problems.

The principal one being :

class A {
     void foo() {}
}

class B {
     override void foo() const {}
}

Add a const foo method to A, and B;foo don't overload the same 
method anymore.