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Path: utzoo!utgpu!utcsri!flaps
From: flaps@utcsri.UUCP
Newsgroups: comp.lang.c
Subject: Re: reserved word 'entry'
Message-ID: <5282@utcsri.UUCP>
Date: Thu, 20-Aug-87 11:44:18 EDT
Article-I.D.: utcsri.5282
Posted: Thu Aug 20 11:44:18 1987
Date-Received: Sat, 22-Aug-87 08:50:23 EDT
References: <402@root44.co.uk>
Reply-To: flaps@utcsri.UUCP (Alan J Rosenthal)
Organization: University of Toronto
Lines: 45
Keywords: entry reserved
Summary: 


In article <402@root44.co.uk> jgh@root.co.uk (Jeremy G Harris) writes:
>Does anybody know what the K&R-listed reserved word 'entry' was for?
>Anybody have a compiler which uses it?

It wasn't for anything, it was one of these 'reserved for future use'
things.  I don't know of any environment which uses it other than to print
"syntax error".

I always assumed that it was modeled on the fortran ENTRY keyword, which
allows multiple entry points to a function.  It's sort of like using
fall-throughs in case statements.

For an example: the slightly misleading structure

	int fullcalculation()
	{
	    ...
	    partialcalculation();
	}

	int partialcalculation()
	{
	    ...
	}

would be replaced by something like:

	int fullcalculation()
	{
	    ...
	
	entry partialcalculation;
	    ...
	}


It's not entirely clear what the advantage is.  Of course, you don't
have to say the formal parameters twice, and they don't have to be pushed
on the stack twice, but this could be optimized out as a special case kind
of tail recursion anyway by either a very smart compiler, or a compiler
implemented by someone who thinks that the 'entry' keyword would make a
big difference.

ajr