Discussion: Rvalue refs and a Move construtor for D

Exil Exil at gmall.com
Wed Sep 4 00:33:06 UTC 2019

On Wednesday, 4 September 2019 at 00:16:06 UTC, kinke wrote:
> On Tuesday, 3 September 2019 at 23:51:43 UTC, Manu wrote:
>> On Tue, Sep 3, 2019 at 2:45 PM Suleyman via Digitalmars-d 
>> <digitalmars-d at puremagic.com> wrote:
>>> I'm still demanding a use case for rvalue ref other than for 
>>> move semantics.
>> That's it; move semantics. That's not a minor thing...
>> Why?
> Because just detecting move-construction/-assignment/'argument 
> moval' can get away with special identifiers for 
> constructor/assignment operator or some special @move UDA, as 
> Suleyman has proposed so far, instead of fully extending the 
> language by rvalue refs, with mangling additions and new 
> overload rules etc.
> It's clear that this would restrict C++ interop, but that's the 
> point - do we want to adopt the C++ approach fully, or keep 
> things simple & tidy at the expense of not being able to 
> represent C++ functions with rvalue refs (except for move 
> constructor and assignment op)?

How would it work with multi-function passing though? With a 
rvalue reference, you are effectively just passing around a 
reference, until the contents of the value are moved. So you can 
pass it through N functions and it won't ever to do a move/copy.

Would you effectively be relying on the compiler to optimize out 
the un-necessary moves, or would they be unavoidable, as they 
effectively are now?

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