Calling Ada from a non-Ada language

[dale.ksc.nasa.gov!rsimonia@ames.arc.nasa.gov (Rick Simonian)]

I'm sure that most will consider this to be gross and unwieldy,
but we need to be able to call Ada routines from non-Ada 
languages.  We first want to solve the problem from C; other
languages need to be addressed later.

I would like to know of any experience doing this in a Unix
environment, both where Ada is the main procedure, and where
C (for example) is the main procedure.  I'm aware of the
obvious problems: how to link the executable if Ada is not
the main, how to elaborate the Ada runtime, use of exceptions, 
passing complex structures, how tasking works, and so forth.

Ada provides a reasonable means of calling non-Ada routines,
but you hit a brick wall going the other way.  This problem
needs to be addressed in order to better integrate Ada into
a heterogeneous environment.

Rick Simonian
Harris Space Systems Corp.
simonian@x102a.ess.harris.com