[dmd-concurrency] draft 4

[Robert Jacques]

On Tue, 12 Jan 2010 17:00:22 -0500, Andrei Alexandrescu  
<andrei at erdani.com> wrote:

>> I know this is a bit of a bike shed, but I'd prefer something shorter  
>> for receiveOnly, (like recv or receive) as A) type-checked message  
>> passing should be the easy/default way to do things and B) it's easy to  
>> define recv!()() to return the unchecked message using a variant. I'd  
>> also like to be able to use recv(tid,i); in addition to recv!(Tid,  
>> int)(); but I haven't been able to get the templates to not clash with  
>> each other.
>
> As of now I'm thinking that receiveOnly will be much more rarely used  
> than receive() with several dispatchers. receiveOnly is very restrictive  
> - see my next message.
>
>
> Andrei

The concept for a receive with many dispatchers has a well know name in  
CSP parlance: the alternative, alt or select (depending on which  
iteration/language you're in) with a set of associated guard statements.

 From some old notes I had on doing CSP in D:

select.roundRobin(
     guard(id_1, (int x) { writefln("from id 1: ",x);} ),
     guard(id_2, (int y) { writefln("from id 2: ",y);} ),
     guard(true,         { writefln("boolean tests are allowed");  } )
);

Although why they didn't just reuse switch and case I don't know.