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Path: utzoo!linus!decvax!harpo!eagle!mhuxi!houxm!ihnp4!inuxc!pur-ee!CSvax:Pucc-H:Physics:hal
From: CSvax:Pucc-H:Physics:hal@pur-ee.UUCP
Newsgroups: net.lang.mod2
Subject: Implicit EXPORT?
Message-ID: <1051@pur-phy.UUCP>
Date: Tue, 11-Oct-83 13:48:21 EDT
Article-I.D.: pur-phy.1051
Posted: Tue Oct 11 13:48:21 1983
Date-Received: Thu, 13-Oct-83 07:15:23 EDT
Organization: Purdue University Physics Dept.
Lines: 52


    This was meant as a followup to Pat Clancy's comments in net.lang
but the followup command posted the response as a separate article.
Therefore I'm posting it here (actually it's more appropriate for this
newsgroup anyhow).  The question concerned the implicit export of record
field types.
-----------

	You misunderstood the question I was asking.
	Given:

DEFINITION MODULE A;
EXPORT foo;
TYPE foo=(whatever,...);
END A.
	and
DEFINITION MODULE B;
FROM A IMPORT foo;
EXPORT bar, proc1;
TYPE bar = RECORD
		fld: foo:
		...
	   END;
PROCEDURE proc1;
...
END B.

	Then,

MODULE user;
FROM B IMPORT bar, proc1;

VAR eg: bar;
    f1: foo;			(* Is this declaration valid? *)
(*      ^ undefined identifier (* or should this be the case?*) *)
BEGIN
	(* assume eg is defined *)
	proc1(eg.fld);	(* as pointed out, this is OK *)
	f1 := eg.fld;	(* this is OK, only if the declaration worked *)
END user.
---------

    The Modula-2 report specifies that the name "fld" is exported with "bar"
but does not mention what the status of "foo" is.  A strict interpretation
would require that "foo" be unknown in the module "user".  Of course, the
compiler knows about "foo", that's not the question.  How, do current
implementations handle this.

Hal Chambers
Physcis Dept.
Purdue University
(...!pur-ee!pur-phy!hal)