Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!ucsd!sdcsvax!ucsdhub!hp-sdd!hplabs!sdcrdcf!trwrb!aero!venera.isi.edu!raveling
From: raveling@vaxa.isi.edu (Paul Raveling)
Newsgroups: comp.software-eng
Subject: Re:  Configuration Management (UNIX Linker)
Message-ID: <4957@venera.isi.edu>
Date: 5 Mar 88 03:26:29 GMT
References: <5303@well.UUCP> <4148@ptsfa.UUCP>
Sender: daemon@venera.isi.edu
Reply-To: raveling@vaxa.isi.edu.UUCP (Paul Raveling)
Organization: USC-Information Sciences Institute
Lines: 39

In article <4148@ptsfa.UUCP> jmc@ptsfa.UUCP (Jerry Carlin) writes:
>
>Actually, since this group is comp.software-eng, I'd like to state my
>opinion that one function per source file is a good way to go. If multiple
>functions per source file are useful for a given situation, they should
>all be strongly related so that if you are planning to use one you would
>typically use all of them rendering the problem moot.
>

	I believe the best software engineering criterion to use
	is to organize functions into modules in such a way as to
	minimize overall complexity.  

	The IBM (Itty Bitty Modules) approach leads to excess complexity
	and lack of appropriate structure in any but the simplest
	software.  I've worked with two sets of software that used
	this approach and paid for it in maintainability -- 
	One was OS/360, the other was various MIL spec software,
	mainly for air data computers.

	For example, one function per file eliminates the ability
	to share a set of data among related functions, but to
	encapsulate it within this set.  The biggest maintenance
	headaches I've encountered have tended to be tracking down
	accesses to public data.

	On the other hand, lumping too many functions into the
	same source file produces the same kind of lack of structure
	and lack of encapsulation as one function per source file.

	In my experience the best-organized software probably has
	averaged 4-6 functions per module, but it's inappropriate
	to look for a general rule of "n functions per module".
	Minimizing complexity sometimes DOES dictate one function
	in many files, but sometimes it may be 10.


---------------------
Paul Raveling
Raveling@vaxa.isi.edu