Path: utzoo!yunexus!geac!daveb
From: daveb@geac.UUCP (David Collier-Brown)
Newsgroups: comp.lang.c
Subject: Re: entry (was Re: Pointers to functions)
Keywords: entry, C, PL/1
Message-ID: <2444@geac.UUCP>
Date: 13 Mar 88 20:55:01 GMT
Article-I.D.: geac.2444
Posted: Sun Mar 13 15:55:01 1988
References: <7811@tut.cis.ohio-state.edu- <7689@pur-ee.UUCP> <585@tuvie> <1988Mar11.221528.1392@utzoo.uucp>
Reply-To: daveb@geac.UUCP (David Collier-Brown)
Organization: The Geac Pl/1.1415 Department
Lines: 45

In article <1988Mar11.221528.1392@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
>               It's also not at all clear that it
>is particularly useful, which is probably why nobody ever did anything
>with the "entry" keyword.

  It was useful in PL/1 for simulating C-like static-to-file
variables and C++-like packages... (sudden thought: ++- should be a
new operator in D).
  It got dropped just about the time it might have proved usefull,
much to my relief. C++ is much cleaner than:

balanced_binary_tree: procedure returns ptr; begin;
	declare 1 tree;
		(2 left, 2 right, 2 ptr) ptr
		based on (p);

	on misallocate goto cleanup;
	allocate (tree) set(p);
	return p;
  cleanup:
	return null;

newleft: entry(p,q) returns ptr; begin;
	declare p, q ptr;
	if (p->left = null) then do;
		p->left = balanced_binary_tree;
		p->left->ptr = q;
	end do;
	else do;
		rebalance(p,q);
	end do;
	return p->left;
end;
...

  The Multicians managed to avoid this almost entirely, the unicians
left it out of the language and the tune-in-next-weekians found a
better way.

  Never let it be said that we aren't making progress.
-- 
 David Collier-Brown.                 {mnetor yunexus utgpu}!geac!daveb
 Geac Computers International Inc.,   |  Computer Science loses its
 350 Steelcase Road,Markham, Ontario, |  memory (if not its mind) 
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