Re: [boost] [coroutine] interface suggestion

Subject: Re: [boost] [coroutine] interface suggestion
From: Giovanni Piero Deretta (gpderetta_at_[hidden])
Date: 2012-09-20 08:23:15

On Thu, Sep 20, 2012 at 12:45 PM, Oliver Kowalke <oliver.kowalke_at_[hidden]>wrote:

> > references are not pointers the c++ . They are aliases; there might or
> > might not be an address somewhere in memory representing the reference,
> > depending on compiler version, optimization level and calling convention.
> > In the sniped below, for example, on a modern calling convention, x will
> > be
> > passed via a register. You can't maningfully get the address of a
> > register.
> > The register might be spilled on the stack when needed, but the stack
> slot
> > location need not be stable and the compiler may assume that the content
> > won't be changed by the user code.
>
> my information was that references are pointers but because they are not
> changeable after initialization the compiler can do arbitrary things with
> it (especially the optimizer).
> OK - the code could cause undefined behaviour for references.
>
> Should bind() deny to bind to references and the coroutine-fn parameters
> must be pointers in this case?
>
> no please!

> Should yield() return a tuple<> instead (as in the current implementation)
> and bind() is not provided?
>

Again, I would prefer that a coroutine would allow later retrieval of the
result value, but I think such a yield (or caller_t::operator()) would be
fine.

You should still consier having yield should return a reference to a tuple.
The tuple itself should be stored on the calling coroutine operator(). And
viceversa of course. Depending on the implementation, it might (or not) be
more efficient.

-- gpd