Re: Libraries in Obj C vs. Java

[Marcus G. Daniels]

>>>>> "SR" == M Lang / S Railsback <address@hidden> writes:

SR> Can we write libraries in Obj C and still use them later if we
SR> write models in Java? Or if we write them now in Java can we still
SR> use them from our Obj C models?

It would not be hard to adapt the technology that connects the Swarm
libraries for Java and COM to work with other Objective C libraries.
It's not terribly complicated to make that work.  Certainly, the SDG
could do it for a fee.  However, since most Swarm users are developing
models, not libraries, it makes little sense for us to make that
bridge since the result of that would just be to keep more users in
the old world of Objective C. 

More user-community investments in Objective C are undesirable because
in the next-generation IMA approach, the easy-to-use configuration
will *not* include languages that don't have existing freely-available
interpreter infrastructure.  Examples of languages that *do* have
freely-available interpreter infrastructure are languages like Java,
JavaScript, Perl, Python, Scheme, and Smalltalk (which is like
Objective C).  Currently, JavaScript and Scheme are working.

Of course, anything is possible, but Objective C would be more
cumbersome to target, especially given Swarm's unusual variations on
Objective C.  It would at least involve an extra compilation for a
pre-installation plug-in.  Not that we even expect to support that
unless someone pays us to do it -- people with large amounts of legacy
code are the sort of folks that could amortize this cost, in terms of
their and our inconvenience.

SR> Probably a more useful question is: how much hassle is it to use a
SR> non-Swarm library that's in a different language than our model?

There are a number of options depending on what the library is and what
language you use for the model.  If the model is in Objective C, and the
library is Fortran, say, then a few Makefile tweaks for link-level integration
would work.  If the model is in Java and the library is Objective C then
you'd probably want to use the kind of bridge I mentioned.  If the library
is C++ and the model is Objective C, then COM stuff might make the most sense.
It really depends...

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