On Mon, Jan 18, 2016 at 8:28 PM, Thiago Macieira <thiago.macie...@intel.com> wrote:
> > Here's what a vector could when resizing do for: > > a) regular type > allocate new block, copy-construct then destroy each element, free old > block > > b) regular type with move constructor > ditto, but move-construct instead > > c) regular type with noexcept move constructor > ditto, but like Peppe said, it can be done in a mass operation that cannot > throw. TBH, I don't see how this implementation would differ from b. In > fact, > the code would be the same as a and b and I'd rely on the compiler > optimising > the rollback code away. > I don't think b) can possibly exist if you want a container to offer the strong guarantee. Once you start moving elements out of the original block, if a move throws, you end up in a broken state. You can't move the already-moved elements back into the original block because that may cause further exceptions. It should be really either a) or c) (i.e. "apply std::move_if_noexcept"). Cheers, -- Giuseppe D'Angelo
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