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Content-type: text/plain
How about the following. I typed this right now so not sure if this is all
correct, but gives you a flavor. IMHO this is an illustration why
procedure types should *not* be dropped from the language. Purists will
say procedure types are not needed, but then purists probably have never
calculated any integrals anyway. The bottom line: do not break away from
50 years of tradition unless you can convincingly argue there is no other
way. Or, if you break away for puristic reasons, then do not complain
people do not want to use the language anymore.
MODULE Integrand;
TYPE
FnType * = POINTER TO RECORD
END;
PROCEDURE (f: FnType) Calculate * (x: REAL), NEW;
BEGIN
RETURN x*x (*just an example*)
END Calculate;
END Integrand.
MODULE Integrate;
IMPORT Integrand;
PROCEDURE Integ (
func: Integrand.FnType;
xMin, xMax, tol: REAL
): REAL;
BEGIN
(* call func like this: func.Calculate (x) *)
END Integrate;
> If procedure types are obsolete, how do I write a library
> procedure that *requires* a functional parameter? Example:
>
> TYPE
> FnType = FUNCTION(x: REAL): REAL;
>
> FUNCTION integral( integrand: FnType; xMin, xMax, tol: REAL): REAL
>
> Sincerely,
> Rex Couture, Ph. D.
> Dept. of Earth and Planetary Sciences
> Campus Box 1169
> Washington University in St. Louis
> 1 Brookings Dr.
> St. Louis MO 63130
>
> Voice: (314) 935-4194
> Fax: (314) 935-7361
> rex{([at]})nowhere.xy--------------------------------------------
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----boundary-LibPST-iamunique-829395378_-_-
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Received on Wed Nov 17 2004 - 19:21:15 UTC