From: Greg Willits <lists@...>
Date: 2012-04-21T01:39:47+09:00
Subject: Re: When are numbers NOT Magic? Example.

Robert Klemme wrote in post #1057330:
> On Thu, Apr 19, 2012 at 7:30 AM, Greg Willits <lists@ruby-forum.com>
> wrote:
>> measurement technology and accuracy. Changing one value's precision
>> string with thousands separators and with a specified precision.
>> <span>
>> <%= float_as_thousands_with_precision(watts, 2) -%>
>> </span>
>>
>> I contend, those are NOT magic numbers.
>
> Certainly not.
>
>> Using the above definitions (and others I found like them), such numbers
>> do not need constants because:
>> -- each number is a single instance (no redundancy)
>> -- each number is independent from the other (no shared cause & effect
>> on precision)
>> -- each number's purpose is very clear from from both the function name
>> and argument name (no need to clarify purpose)
>
> But a constant's name goes a long way in documenting the meaning.

Generically, I agree that's a good purpose for a constant, but in this 
case, it seems to me that

<%= float_as_thousands_with_precision(watts, PRECISION_OF_WATTS) -%>
isn't any clearer or better documented than
<%= float_as_thousands_with_precision(watts, 2) -%>

I think that's the crux of what I see. To me, the latter can't really be 
improved upon. It can be different, but is the extra code really adding 
value? Your FORMATS idea is interesting (and useful for a repeatedly 
used value), but in the end isn't it a variation on a list of constants?

Anyway, thanks for your comments. I appreciate your taking the time to 
noodle on my epistle.

-- gw

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