From slices to perfect imitators: opByValue

[Timon Gehr via Digitalmars-d]

On 05/08/2014 08:55 AM, Jonathan M Davis via Digitalmars-d wrote:
> As far as I can see, opByValue does the same thing as opSlice, except
> that it's used specifically when passing to functions, whereas this code
>
> immutable int [] a = [1, 2, 3];
> immutable(int)[] b = a[];
>
> or even
>
> immutable int [] a = [1, 2, 3];
> immutable(int)[] b = a;
>
> compiles just fine. So, I don't see how adding opByValue helps us any.
> Simply calling opSlice implicitly for user-defined types in the same
> places that it's called implicitly on arrays would solve that problem.
> We may even do some of that already, though I'm not sure.

Automatic slicing on function call is not what actually happens. You can 
see this more clearly if you pass an immutable(int*) instead of an 
immutable(int[]): there is no way to slice the former and the mechanism 
that determines the parameter type to be immutable(int)* is the same. 
(And indeed doing the opSlice would have undesirable side-effects, for 
example, your pet peeve, implicit slicing of stack-allocated static 
arrays would happen on any IFTI call with a static array argument. :o) 
Also, other currently idiomatic containers couldn't be passed to functions.)