Re: Do I Really Need A Supervisor?

[dewar@merv.cs.nyu.edu (Robert Dewar)]

Sam said

<<What do you mean? He didn't write "a 'main' procedure", but "a main
procedure" which is quite different.>>

Bob meant what he said, in Ada 83, a main subprogram (not necessarily
called main, of course) is required, but this requirement is eliminated
in Ada 95. 

Seems a silly change to me, but it is a harmless enough one.

GNAT supports this, but only with some fiddling (you need a dummy C main
program with a call to adafinal and adainit, and then you bind with
-gnatn, saying there is no main program).

The idea is that you can do all your processing in elaboration code, a 
perfectly horrible way of structuring a program (which is why I think
this is a silly change), but one that makes perfectly good technical 
sense.

Note: I find that many Ada programmers get carried away with elaboration
code. They think "hey! isn't this neat, I can do everything at elaboration
time", and as usual when people get the "hey! isn't this neat" thought, they
are in fact creating obscure junk :-)

There is even one Ada compiler with a null main program where each pass is
a package that does its work in package elaboration code, and pragma
Elaborate is used to make sure that the passes are executed (i.e. elaborated
at package elaboration time) in the right order -- hey! isn't that neat? :-)