Re: [Boost-users] [Boost] [Interprocess] Use of Boost.Move in interprocess affecting causing compilation errors with 1.46

Subject: Re: [Boost-users] [Boost] [Interprocess] Use of Boost.Move in interprocess affecting causing compilation errors with 1.46
From: Lars Hagstrom (lars_at_[hidden])
Date: 2011-03-10 09:35:28

Thanks for the explanation!

Now I know that I haven't misunderstood completely... :-)

Cheers
Lars

2011/3/10 Ion Gaztañaga <igaztanaga_at_[hidden]>

> El 10/03/2011 7:58, Lars Hagstrom escribió:
>
>  Hi all,
>>
>> I'm having a problem compiling some code with boost 1.46 that was
>> compiling fine with 1.36 to 1.43 (or thereabouts). It appears that this
>> is somewhat related to the use of Boost.Move in the Boost.Interprocess
>> library.
>> I have tried to read up a bit on Boost.Move, but have failed to quite
>> understand what of it applies to me.
>>
>
> You are right. The new emulation (which is what Boost.Move will implement)
> is more efficient in several cases but forces you to define the assignment
> operator. Full explanation here:
>
>
> http://igaztanaga.drivehq.com/libs/move/doc/html/move/two_emulation_modes.html#move.two_emulation_modes.optimized_mode
>
>
>  Is this the way it is meant to be? I was fine with the
>> compiler-generated ones before...
>>
>
> Yes, it was, but suboptimal for copyable and movable classes like
> containers. In the old approach if class A was movable and copyable, this
> would call the copy assignment instead of the move assignment
>
> A a (...);
> a = A();
>
> ...and you could not reuse A()'s string memory in a. If your class
> implements copy assignment taking by value, this limitation does not arise,
> but value-taking copy assignment is suboptimal for containers. Sorry for the
> breaking change.
>
> Best,
>
> Ion
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