On Friday, 29 June 2018 at 07:37:46 UTC, FeepingCreature wrote:
On Friday, 29 June 2018 at 07:31:42 UTC, Eugene Wissner wrote:
You can move only exactly the same type. with opAssign you can
assign a differnt type. So opAssign should forward assignment
to the underlying type if you assign nor Nullable!T nor T.
Sorry, that was unclear; I meant to ask for usecases for
T::opAssign(T). Maybe the reason to allow this is just that
it's a generalization of the actually useful T::opAssign(S),
but I want to know if there's a specific usecase for calling
specifically T::opAssign(T).
Not an exact answer, but there is a DIP to add kind of move
constructor to D:
https://github.com/dlang/DIPs/blob/master/DIPs/DIP1014.md
And Andrei mentioned plans to write a DIP to add a copy
constructor (and maybe deprecate postblit some day, o leave at as
is).
So yes people have use cases where they have to access the source
instance (like in T.opAssign(T)).
The first DIP mentions counting of all instances in the
application, it can be some kind of "intelligent" assignment,
where you copy/move only some parts of the source instance (and
not copy/move it completely) or adjusting the internal
references/structure of the source instance - something like
this, I think.
