Re: re-use and concurrency

[mintaka!ogicse!hsdndev!encore!jcallen@bloom-beacon.mit.edu (Jerry Callen]

Various people have discussed the problem of needing "sequential" and
"concurrent" implementations of reusable components. Not only are multiple
implementations needed, but you also have to decide which one to use.
While this might seem easy, what if you are building yet another component
that may be used in either tasking or non-tasking programs?

Seems to me the right way to solve this is with the library manager;
put the "sequential" and "concurrent" implementations in separate libraries
and them select the one you need at link time. This does require that your
compiler's library scheme allow specs and bodies in different libraries,
and that the set of libraries used be changable at link time. I know
that (at least) the Intermetrics, Rational and Verdix compilers will
allow this, with varying levels of kluginess.

What would REALLY be nice is to have the linker select the right library
for you, based upon whether or not tasking is in use. Some linkers already
know if tasking is present, so such automatic library selection SHOULDN'T
be a difficult thing to offer, eh?

-- Jerry Callen
   jcallen@encore.com