What would you do...

[Andrew Wiley]

On Thu, Dec 8, 2011 at 5:53 PM, Sean Kelly <sean at invisibleduck.org> wrote:
> On Dec 8, 2011, at 8:23 AM, Manu wrote:
>>
>> Just digging through concurrence.d since the docs are pretty bare, and I've come across this pattern, which raises a pretty worrying alarm to me. I wonder if this is common in D libraries...
>>
>> ...
>>
>> No overload, receives a tuple, and assumes that static-if the first tuple item is IMPLICITLY CONVERTIBLE to a Duration, I must be calling the 'overload'...
>>
>> I guess this means I can never pass a Duration in a message to the non-timeout receive()... or anything that is implicitly convertible to a Duration.
>
> Right.  The only thing you can pass to receive() are functions taking one or more parameters.  mbox.get() itself is actually pretty lax in enforcing this because it relies on the caller to do most of the filtering (via checkops).  This should be safe since the mbox itself is private.  I suppose I could have done this a different way, but overloading when one function has (T…) args is a bit weird.
>
>
>> This would seem to be a very obscure hidden bug to me. Is this a common pattern in D?
>
> It's probably the only case.
>
>
>> I certainly wouldn't want to be tracking down this bug on build night... Is there something I've missed here? Some sort of safeguard I've overlooked?
>
> See above.  MessageBox is private and receive() does the parameter checking.

This is somewhat of a threadjack, but I was looking at making a
lighter actor-like abstraction for message passing, and possibly
making it compatible with std.concurrency, and I saw this:
"The general idea is that every messageable entity is represented by a
common handle type (called a Cid in this implementation), which allows
messages to be sent to in-process threads, on-host processes, and
foreign-host processes using the same interface."

As far as I can tell, Cid does not appear outside the documentation at
the top of std.concurrency, and Tid is a direct linkage to
std.concurrency's private mailbox implementation, so I was wondering
what the best way to extend message-passing functionality to another
type would be.