From: Robert Klemme <bob.news@...>
Date: 2005-05-27T17:50:19+09:00
Subject: Re: A different perspective on Ruby.

Glenn Parker wrote:
> Brian Schr�der wrote:
>> On 26/05/05, gsinclair@gmail.com <gsinclair@gmail.com> wrote:
>>> ES wrote:
>>>
>>>> http://www.ericw.org/rants/showrant.psp?rant=ruby
>>>
>>> "It's 5.abs for absolute value, but Math.sqrt(5) for square root."
>>>
>>> Good point.  That bugs me too.  abs is a *function*, not logically a
>>> method.
>>
>> Why not 5.sqrt instead.

+1

> Hmmm, prefix, postfix, or infix?  Functional or object-oriented?
> These are bottomless questions.
>
> One justification for sqrt(5) would be that "sqrt", works on more than
> one class of objects (Fixnum, Bignum, Rational, etc).  So does "abs"
> for that matter, and I'm not crazy about 5.abs.  As a method, sqrt
> would have to be defined in every applicable class, either with new
> code or as an included module.  This spreads the definition out,
> which complicates maintainence.

This is not true, for two reasons:

First, there is indeed a place to put functions that have the same
implementation for all numeric types - so it does not have to spread:

>> Fixnum.ancestors
=> [Fixnum, Integer, Precision, Numeric, Comparable, Object, Kernel]
>> Bignum.ancestors
=> [Bignum, Integer, Precision, Numeric, Comparable, Object, Kernel]
>> Float.ancestors
=> [Float, Precision, Numeric, Comparable, Object, Kernel]

>> ObjectSpace.each_object(Class){|cl| p cl if cl.ancestors.include?
Numeric}
Bignum
Float
Fixnum
Integer
Numeric

Second, it's most likely that you actually *want* different
implementations for performance and optimization reasons (see the recently
discovered bug with exponentiation).

> Another reason is that the prefix style, sqrt(5), is somewhat closer
> to the typical mathematical notation.  I can't think of any unary
> mathematical operations that are naturally postfix, unless you count
> C++'s post-decrement and post-increment.

Well, this can remain in place as a simple forward to not break
compatibility

def Math.sqrt(n) n.sqrt end

> This is all just criticism of library design, which is very much a
> matter of style and taste.  The "standard" library could stand some
> attention to smooth out these style bumps, possibly by allowing either
> prefix or postfix styles whenever possible.  Then questions of style
> would be forwarded to the programmer.

True.

Kind regards

    robert