Re: first sight

From: bill_kempf (williamkempf_at_[hidden])
Date: 2002-01-16 10:00:26

--- In boost_at_y..., Beman Dawes <bdawes_at_a...> wrote:
> At 12:05 PM 1/15/2002, bill_kempf wrote:
> 
>  >Cooperative/deferred cancelation most certainly can be done safely
>  >and effectively in C++.  Doing so portably puts a few constraints 
on
>  >us.  For instance, Boost.Threads is going to have to use an actual
>  >C++ exception here (I believe), while the standard could just use
>  >a "kissing cousin" to the exception (i.e. the standard could make 
the
>  >type non-catchable).
> 
> To add Boost.Threads (or any other threading library) to the C++ 
standard 
> will require a number of additions to the standard document.  I 
doubt that 
> is either surprising or upsetting to most committee members.
> 
> AFAIK, however, the current Boost.Threads does not require changes 
to 
> current C++ compilers which already support native platform threads.
> 
> That makes it a MUCH easier to sell to the compiler vendors, who 
are well 
> represented on the committee.  They can see that it already works, 
and 
> already works with their compiler.  It also means users can benefit 
today, 
> rather than having to wait for years.
> 
> Likewise, there are strong advantages if it is possible to 
implement 
> cooperative/deferred cancellation via an actual C++ exception.  
Compilers 
> don't have to be changed.  We can show that it works.  Can be used 
today.
> 
> If the wording in the standard gives the implementors leeway to 
build in 
> a  more efficient "kissing cousin", fine.  But it is a huge win if 
a 
> moderately efficient portable (at least between compilers on the 
same 
> platform) implementation can be done in standard C++.

Agreed, and the final decision is, of course, up to the committee.  
I'm just trying to "feel out" the pros and cons of using an actual 
exception, which can be caught in a catch(...) block.  If there are 
compelling reasons to want the "exception" to be non-catchable then I 
can present these reasons to the committee and they can decide 
whether or not it's worth requiring a language change to allow for 
this "kissing cousin".

Bill Kempf