Path: utzoo!mnetor!uunet!husc6!mit-eddie!ll-xn!ames!necntc!linus!philabs!pwa-b!mmintl!franka
From: franka@mmintl.UUCP (Frank Adams)
Newsgroups: comp.software-eng
Subject: Re: examples complexity measure usage
Message-ID: <2656@mmintl.UUCP>
Date: 13 Jan 88 23:52:36 GMT
References: <398e2f3e.fed5@apollo.uucp>
Reply-To: franka@mmintl.UUCP (Frank Adams)
Organization: Multimate International, E. Hartford, CT.
Lines: 55

In article <398e2f3e.fed5@apollo.uucp> marc@apollo.uucp (Marc Gibian) writes:
|As promised, here are some examples of decreasing the quality of code
|while reducing the complexity measure value. ...  The contractual
|requirement was that every procedure and function have a McCabe value less
|than or equal to 10.  

One general comment: these examples suggest that, at least at the current
level of development, the complexity measures are better as a tool for
evaluating code than as a goal.  They make a better servant than a master.

|original fragment:
|
|   if (a == value1) then
|      y = target1;
|[...]
|   else if (f == value6) then
|      y = target6;
|   end if;
|
|transformed fragment:
|
|   new_func((a == value1), target1);
|[...]
|   new_func((f == value6), target6);
|
|with new_func defined as:
|
|new_func(relation_value, target)
|{
|   if (relation_value) then
|      y = target;
|   end if;
|}

Two comments here:

It seems to me that a metric should regard an "if ... else if ... ... [else
...]" construct as approximately equivalent in complexity to an "if ... else
..." construct.

It seems to me also that use of global variables should be penalized.  As a
first approximation, one might include a cost of 1 for each global variable
referenced by the program.  (This still leaves the option of putting several
more or less irrelevant globals into a structure, to cut down on the number
of globals.  Perhaps each component explicitly referenced should cost 1?)

|I agree with the goal of using a metric to measure the characteristics of
|code, I simply believe that no metric now exists that truly measures the
|qualities that people (management, customers) want to measure.

This seems like a reasonable summary.
-- 

Frank Adams                           ihnp4!philabs!pwa-b!mmintl!franka
Ashton-Tate          52 Oakland Ave North         E. Hartford, CT 06108