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From: mike@turing.UNM.EDU (Michael I. Bushnell)
Newsgroups: comp.lang.pascal,comp.bugs.misc
Subject: Re: pxp and null
Message-ID: <927@unmvax.unm.edu>
Date: 10 Apr 88 22:37:51 GMT
References: <252@gould.doc.ic.ac.uk>
Sender: news@unmvax.unm.edu
Reply-To: mike@turing.UNM.EDU.UUCP (Michael I. Bushnell)
Organization: University of New Mexico, Albuquerque
Lines: 27

In article <252@gould.doc.ic.ac.uk> iwm@doc.ic.ac.uk (Ian Moor) writes:
>The pxp  BSD Pascal prettyprinter inserts the word `null' in places
>where a null statement is legal : if B then P else; becomes 
>if B then P else null;. Null is not a legal Pascal statement and
>causes non BSD Pascal processing tools to complain, (eg. ptc : Pascal to
>C converter). As pxp has an {\HUGE FLAME undocumented} switch -O for
>removing `others' in case statements it is used in compiling TeX --
>and the Tangle  preprocessor generates statements with null cases that
>get mangled as described above.

While null statements are ALWAYS legal...[take a look at the syntax],
the procedure name "null" is required to be provided in every ISO
comformant compiler.  It is a procedure which does nothing.  Berkeley
pc just ignores it instead of generating a call.  So, it IS standard
pascal.  

Furthermore, in my opinion, the placement of an explicit call to null
makes the structure much more readable.
                N u m q u a m   G l o r i a   D e o 

			Michael I. Bushnell
			HASA - "A" division
14308 Skyline Rd NE				Computer Science Dept.
Albuquerque, NM  87123		OR		Farris Engineering Ctr.
	OR					University of New Mexico
mike@turing.unm.edu				Albuquerque, NM  87131
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