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From: adam@visix.com
Newsgroups: comp.object
Subject: Re: named parameters and verbosity [was: Functions without side effects]
Message-ID: <1991Jun26.185707.26149@visix.com>
Date: 26 Jun 91 18:57:07 GMT
References: <130242@tut.cis.ohio-state.edu> <4888@osc.COM> <72893@microsoft.UUCP> <1991Jun21.013944.23970@netcom.COM> <20445@alice.att.com> <1991Jun26.001847.24239@netcom.COM>
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In article <1991Jun26.001847.24239@netcom.COM>, jls@netcom.COM (Jim Showalter) writes:

> argl (4.5, 8, INCR, "bargl");

> Even with a more readable name for the function, the arguments remain
> essentially content-free without a lot of surrounding context. The whole
> point of named parameter association is to provide the missing semantics
> at the point of call, to wit:

> argl (Azimuth => 4.5, Inclination => 8, Mode => INCR, Options => "bargl");

I almost never put raw constants in my code, both because of the thin
semantics and because changing the constants becomes a ridiculous
hunt-and-kill exercise.  ("Search-and-replace: 5 [CR] with: 6 [CR]").

I would write the above in C as follows:

In a header file, perhaps argl.h:

#define STANDARD_AZIMUTH	4.5
#define	STANDARD_INCLINATION	8
#define STANDARD_OPTIONS	"bargl"

In the code:

argl( STANDARD_AZIMUTH, STANDARD_INCLINATION, INCR_MODE, STANDARD_OPTIONS );

Other common parameter sets might be called SECONDARY_AZIMUTH and so on.
Derived or continuous values would necessarily be stored in variables, which
I could then name accordingly.

The primary motivation for all this is actually to provide a single maintenance
point (the header file) for parametrizing the behavior of the code.  The semantics
part is simply choosing appropriate names.


> Look, I'm not saying the advent of named parameter association will 
> feed all the world's children, but I do tend to get a little hot under
> the collar when people--the very people you accuse me of inventing as
> straw men, by the way--respond to every advance in code readability with
> the "verbose" label. I've said it before and I'll say it again--there
> is nothing wrong with most hackers that couldn't be fixed with a remedial
> course in touch typing...

Some people who complain about verbosity are hackers.

Some people who complain about verbosity have given the matter a lot of 
thought and have useful points to make.

Sometimes it's easy to confuse the two.


Adam