what operator(s) should I overload to prevent this?

[Steven Schveighoffer]

On 10/16/17 8:00 AM, drug wrote:
> I refactored `MyStructure` added own implementation of malloced array 
> based on pureRealloc/pureFree instead of dynamic array I used before and 
> now I have error:
> Error: cannot implicitly convert expression get(msg.getData()) of type 
> const(MyStructure) to MyStructure.
> 
> What operators should I overload to let this conversion? I've tryed 
> opCast and it fails in other call sites, also I've tried opAssign - it 
> didn't works, what worked is wrapping in ctor - MyStruct(const_var). But 
> using ctor is not convenient.
> 

The issue is:

int[] -> const(int)[].

This is an implicit cast from a mutable array of mutable data to a 
mutable array of const data. There is no way to "hook" this properly.

What you need is:

MyArray!int -> MyArray!(const(int))

But D doesn't do this implicitly. It can't, as you could implement 
MyArray!(const(int)) to be completely different from MyArray!int.

If you define opCast(T : MyArray!(const(T))), then it requires an 
explicit cast, you need an implicit one. You could use alias this, but I 
don't think it's as smooth.

Complicating things further, you have template functions like this:

foo(T)(const(T)[])

Where D is smart enough to pull out the T there. I don't think it works 
with MyArray.

-Steve