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Subject: Re: [boost] [gsoc] Boost.Process done
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2010-09-09 07:07:06

Boris Schaeling wrote:
> On Wed, 08 Sep 2010 03:37:52 +0200, Ilya Sokolov
> <ilyasokol_at_[hidden]> wrote:
> init_stdout_behavior() would need to make sure that stream
> behaviors are initialized only once (not that there are
> multiple pipes created). But then it's difficult again to
> reuse a context object as it would need to be reset explicitly.
> But this could be done in create_child() again. -
> Comments?


> > I expect that if some std stream is closed in the calling process,
> > the default constructor of the context class doesn't throw anything.
> > As I see it, the bp::handle should have a "dont-close" flag and
> > bp::behavior::inherit shouldn't call dup() or DuplicateHandle().
> The reason why bp::behavior::inherit calls
> dup()/DuplicateHandle() is that a parent closes a child's
> handles (and a child a parent's handles; this is done in
> create_child()). Otherwise both processes would have a read
> and write end open when a pipe is used. Without a
> dup()/DuplicateHandle() a parent would close its own standard
> streams if it wants the child to inherit them. I think it also
> makes logical sense to automatically close the streams of the
> other process?
> As I also think the default constructor of context shouldn't
> throw: What if we add another optional parameter to
> bp::behavior::inherit? A bool variable could be used to
> indicate whether bp::behavior::inherit should throw if
> dup()/DuplicateHandle() fails. By default it throws - but it
> doesn't when used by the default constructor of context?

Perhaps policies could manage the degrees of freedom in behavior? Doing so would give names to the various behaviors you've been discussing and would make more operations implicit once the desired policy is specified.

Rob Stewart robert.stewart_at_[hidden]
Software Engineer, Core Software using std::disclaimer;
Susquehanna International Group, LLP

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