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From: David Abrahams (dave_at_[hidden])
Date: 2004-04-19 11:26:29

Andrea Torsello <torsello_at_[hidden]> writes:

> David Abrahams wrote:
>> My library is not relying on it being enough. It's just turning off
>> the mechanisms needed for non-RVO'ing compilers where appropriate.
> This is clearly the best thing, which leaves us where we do not provide any
> X(X const &) constructor (explicit or implicit) unless the compiler
> requires it.

Uh, no: when turning off the mechanisms needed for non-RVO'ing
compilers we supply a non-explicit X(X const&) ctor, and no X(X&)

>>>>> You still need to convert to temporary in initializer lists, since
>>>>> you cannot use the assigment constructor there, but most likely you
>>>>> would have to do it anyway.
> [...]
>> That's what the explicit "move(x)" function is for:
> exactly, my point was that in initialization lists you probably need to
> convert to temporary with the move(x) function. By "convert to temporary" I
> meant the X::temporary type I had in my examples. The move_from<X> type in
> your code.

Right... but that "conversion to temporary" is not the same as
*actually* converting to a C++ temporary, which involves making a

>> Considering that most/all of my ctors' logic is in the initializer
>> list and that the two ctors' initializers will be different, I like
>> having a way to make them the same.
> [...]
>>> Yes users would still have to provide the initializer lists.
>> Only one initializer list need be provided, using implicit_cast<> if
>> neccessary.
> With complicated initializer lists, I agree that one doesn't want to
> duplicate the list. I guess that this is a personal coding-style issue.

Yes. And you can take either approach with both technique 1 and
technique 2.

Dave Abrahams
Boost Consulting

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