[boost] Re: shifted_ptr: why?

From: David B. Held (dheld_at_[hidden])
Date: 2003-10-02 11:32:03

"David Abrahams" <dave_at_[hidden]> wrote in message
news:uekxvrc38.fsf_at_boost-consulting.com...
> > [...]
> > I wouldn't call it "mere vapor".
>
> Well, it's easy for you to say; you're working on it!  Is the code
> available publically somewhere?

It's been in the sandbox for ages, at least until I created an intentionally
"non-portable" copy on my own CVS server.

> > [...]
> > Rather, I'd call it "a challenge to port".  So far, gcc 3.3 is the
> > only compiler that passes all the tests.
>
> Last I'd heard there were still-unsolved exception-safety issues in
> all versions.  Is that fixed now?  That would be great.

I guess it depends on what you call "unsolved exception safety
issues".  You can solve any exception safety issue with a suitable
number of constraints on user code (the extreme case being "user
code will not throw any exceptions"). ;)  So part of my "solution"
was to re-arrange the way smart_ptr manages its resources, and
part of it was to write a policy interface specification that states
exception safety requirements for policies.  The latest version of
the code is available on CUJ at:

http://www.cuj.com/documents/s=8890/cujexp0310alexandr/smart_ptr.zip

The table is not quite ready, but is about 98% done, and might
appear in a future version of CUJ.  I suspect you might be
dissatisfied with the way I "solved" some of the safety issues
with user constraints, but I don't think the work required to
remove those constraints justifies the additional safety.

> [...]
> Why don't you make the code and tests available for people to
> look at?  We have a lot of porting expertise here at Boost...

Sure.  And it's been sitting in the Boost sandbox under policy_ptr
for quite a few months.  In fact, it was one of maybe the first
6 or 7 libraries to get into the sandbox.  It just seemed that
nobody else was interested in wading through the code.

Like I said, the latest version, which includes all the tests, is on
my own CVS server, but if people are really interested in
helping to port it to other platforms, I will update the sandbox
with the latest version.  The tests aren't technically complete,
because one issue that has remained unresolved for quite a
while is how to deal with move policies.  So there are no
tests for the move configuration, and if you do an archive
search, you can see why in a discussion here on Boost.  At
the least, though, people can get started with the CUJ files.
They should contain everything needed to run the tests on gcc 3.3.

Dave

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