rvalue references

[kenji hara]

Temporaries which created on stack to pass an address to `scope ref`
parameter would be destroyed after the "current statement/expression".

T rvalue();

void foo(scope ref T) { ... }
foo(rvalue());   // here is "current statement/expression"
// lowered to: { auto __tmp = rvalue(); foo(__tmp);  __tmp.~this(); };

Note that the lifetime of taken rvalue is mostly same as non-ref parameter
case.
void bar(T arg) { ... arg.~this(); }
bar(rvalue());
// the rvalue argument is moved into the function 'bar', and destroyed
inside function.

Kenji Hara


2013/4/24 Diggory <diggsey at googlemail.com>

> On Wednesday, 24 April 2013 at 00:54:12 UTC, kenji hara wrote:
>
>> 2013/4/24 Manu <turkeyman at gmail.com>
>>
>>  "The r-value being passed is assigned to a stack allocated temporary,
>>> which has a lifetime that is identical to any other local variable, ie,
>>> the
>>> lifetime of the function in which it appears."
>>> There, I defined it.
>>>
>>>
>> Good definition. If add more,
>> "getting address of "scope" parameter would be disallowed, at least in
>> @safe code, because it would be regarded as the escape of stack allocated
>> temporary."
>>
>> Kenji Hara
>>
>
> Why does the temporary need to exist any longer than the current
> statement? (the current lifetime of temporaries are the statement or
> expression). Surely any longer is just wasting stack space.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puremagic.com/pipermail/digitalmars-d/attachments/20130424/9e96e9cb/attachment.html>