[cpp-threads] Re: Thread API interface tweaks

[Nick Maclaren]

I am surprised that there are so many CCs, because I don't like them
on mailing lists.  If most people do, I can try to remember to add
them, but will indubitably forget.

Kevlin Henney <kevlin at curbralan.com> wrote:
> 
> This was not the particular usage I had in mind. Agreed, it does not 
> appear to be massively useful, although it is plausible. However, 
> banning things that are not massively useful but are plausible doesn't 
> appear to be a necessity, and even seems a little harsh in this case. 
> What I had in mind was the fact that multiple threads could wait for the 
> completion of a thread based on a future<void>. Although it is an edge 
> case, I reckon it would be more surprising to disallow future<void> than 
> to allow it, and I reckon following the principle of least surprise 
> would just tips the balance here.

Well, I can think of a fair number of uses for void futures, so it
would be more than just surprising if they are banned.  For example:

A database or I/O system could spin off output, close or similar
operations with no interest in the result, except for success or
failure.  That could be 'returned' either in a global variable or
by an exception.  Also, the wait function could be a 'wait for all
futures on this list and stop the program'.

Now, you can reasonably say that this a poor programming style (I
don't agree, but it is a matter of taste), but it assuredly is a
common paradigm.



Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:  nmm1 at cam.ac.uk
Tel.:  +44 1223 334761    Fax:  +44 1223 334679