ref auto getRange() return scope move struct ?

Jonathan M Davis newsgroup.d at
Fri Aug 16 16:22:27 UTC 2019

On Friday, August 16, 2019 8:14:52 AM MDT Newbie2019 via Digitalmars-d-learn 
> On Friday, 16 August 2019 at 13:51:49 UTC, Jonathan M Davis wrote:
> > It is not possible to prevent moving in D as things currently
> > stand. DIP 1014 will need to be implemented to either hook into
> > moves or to prevent them. However, once DIP 1014 has been
> > implemented, I would expect the result to be that what you're
> > trying to do here simply wouldn't work if you disallowed
> > moving, since DIP 1014 doesn't affect when the compiler does a
> > move. It just allows you to hook into when a move takes place
> > so that you can do stuff like adjust pointers, and presumably,
> > if you @disable the function that hooks into the move, moving
> > will then be disabled (though IIRC, that's not explicitly
> > called out in DIP 1014; it's just what would naturally fall out
> > from how @disable works).
> >
> > - Jonathan M Davis
> Thanks for the very helpful explain, I will try find some work
> around to fix this.
> One more question: If the struct has "@disable this() ;@disable
> this(this) ;",   and the instance is stored into other struct
> member or local|global vars,  it will never moved again?

@disable this() disables default initialization and @disable this(this)
disables copying. Neither of them has anything to do with moving. If you
stick a struct in another struct, and the outer struct is moved, then the
inner struct is moved, because it's part of the outer struct. A static
variable shouldn't ever be moved by the compiler, though anyone could choose
to use std.algorithm's move on it. Similarly, if you put an object on the
heap, the compiler isn't going to move it. If it were inside a dynamic
array, then the runtime might copy it (though if you've disabled default
initialization or copying, I don't think that the type can be put in a
dynamic array), but aside from std.algorithm's move (or another function
that does something similar), it shouldn't ever end up being moved.

- Jonathan M Davis

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