From: Yoann Padioleau <padiolea@...>
Date: 2001-09-24T21:14:25+09:00
Subject: [ruby-talk:21628] Re: Ruby/objects book in style of The Little Lisper

Kevin Smith <kevinbsmith@yahoo.com> writes:

> --- Christopher Sawtell <csawtell@paradise.net.nz> wrote:
> > > The question is: can I pull it off? To see, I wrote the
> > first chapter, 
> > > which you can find here:
> > >
> > <http://www.visibleworkings.com/little-ruby/Chapter1.pdf>
> 
> I think it's promising. I do think you could pull it off,
> but it's definitely not "there" yet, for me. I haven't read
> the original, so I have no idea how this compares in style.
> 
> A few comments, which you can take or leave as you wish:
> 
> 1. Pet peeve #1: factorial should not be implemented using
> recursion. It's just a loop. Simpler. Faster. Safer.
> 
> # warning: untested code ahead!
> def factorial(n)
>   result = 1
>   n.downto(2) do | value |
>     result *= value
>   end
>   return result
> end

Your version is certainly not simpler and safer.
the recursive version is more close to the specification of the problem.

> 
> 2. Pet peeve #2: programming books that focus on math. I
> don't mind having factorial in there somewhere, but putting
> numbers first will turn off a lot of non-math folks, I
> think.
> 
> 3. The first function in your book is pretty complex. I
> would tend towards something simpler. In the numbers realm,
> a method that returns n*n, or n*2. In the words realm, a
> method that always returns "Bob" or something, perhaps?
> 
> 4. The persona on the right seems more knowlegable than I
> would expect. Describing the factorial function in English
> would be reasonable, for a math-person, I suppose. But a
> non-math person won't be able to relate.
> 
> I was surprised that the right side introduced most of the
> terms, like "while loop", "message", "argument", and
> "self". I guess it's part of the style.
> 
> 5. Naming a method factorial2 is confusing. I thought it
> might be factorial 2 aka factorial(2) at first.
> 
> 6. To answer your question about "object variables", I do
> in fact call them "object members" sometimes. Perhaps you
> could postpone "instance", or just punt and say they're
> called instance variables "just because".
> 
> 7. The pace so far seems somewhat uneven. Sometimes we jump
> ahead further than I'm comfortable with, or make passing
> references to things we haven't covered yet. I chalk all of
> that up to it being an early draft.
> 
> If it's something you want to do, I say "go for it!" Be
> sure to get plenty of feedback from typical members of your
> sample audience so by the time you publish it's a gem.
> 
> Kevin
> 
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-- 
Yoann  Padioleau,  INSA de Rennes, France,   http://www.irisa.fr/prive/padiolea
Opinions expressed here are only mine. Je n'�cris qu'� titre personnel.
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