From: Josef 'Jupp' Schugt <jupp@...>
Date: 2006-10-28T05:48:14+09:00
Subject: Re: simple math question

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Robert Oliver wrote:
| On 10/26/06, Wilson Bilkovich <wilsonb@gmail.com> wrote:
|>
|> class Fixnum
|>   def even?
|>     (self % 2).zero?
|>   end
|>   def odd?
|>     !even?
|>   end
|> end
|>
|>
| I normally do that, but I remember somewhere reading that it was
| bad form to not include the return statement. I'm not sure where
| this was. Is anyone familiar with this syntax quasi-rule?

It is a programming-paradigm-dependent semantics rule. If one follows
the functional paradigm, one would write leap? in this way:

class Fixnum
~  def leap?
~    if (self % 400).zero?
~      true
~    elsif (self % 100).zero?
~      false
~    elsif (self % 4).zero?
~      true
~    else
~      false
~    end
~  end
end

if one follows the proceural paradigm one would rather write

class Fixnum
~  def leap?
~    if (self % 400).zero?
~      return true
~    elsif (self % 100).zero?
~      return false
~    elsif (self % 4).zero?
~      return true
~    else
~      return false
~    end
~  end
end

Bad style came into play if one would write something like

class Fixnum
~  def leap?
~    if (self % 400).zero?
~      return true
~    elsif (self % 100).zero?
~      return false
~    elsif (self % 4).zero?
~      return true
~    end
~    false
~  end
end

because in this case one starts with the procedural paradigm and
switches to the functional paradigm. An example of bad style were:

class Fixnum
~  def leap?
~    return true  if (self % 400).zero?
~    return false if (self % 100).zero?
~    return true  if (self %   4).zero?
~    false
~  end
end

While not being necessary it improves code to add a return in order
to stick to the procedural paradigm.

class Fixnum
~  def leap?
~    return true  if (self % 400).zero?
~    return false if (self % 100).zero?
~    return true  if (self %   4).zero?
~    return false
~  end
end

Some rules of thumb:

~ - Use or avoid return consistently.

~ - Make your code reflect your intention to the maximum extend
~   permited by the language you use - if you want a procedure to
~   return some value use "return", if you want a function to evaluate
~   to some value don't.

HTH,

Jupp
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