From: "Peña, Botp" <botp@...>
Date: 2002-11-26T12:00:30+09:00
Subject: Re: [FAQ] Why isn't 'x++' or 'x--' valid?

Hi sir Gavin Sinclair [mailto:gsinclair@soyabean.com.au]:

You wrote:
> [snip]
> At best, x++ could be syntax sugar for 'x = x + 1', but for 
> whatever reason - be it a diminished appetite for sugar, or 
> perhaps no intention to mislead - the creator of Ruby did not 
> include these operators/methods.


Matz indeed suggested long way back that this would be possible but only as
a syntax sugar (maybe preprocess it to .succ/.next/+=/-=). Considering a lot
of "surprises" lately, I would vote for this.

The ++/-- has become a universal idiom for a lot of programmers, just like
"f*ck y*u" idiom has been known worldwide (heck even aborigines say it -pls
excuse my language, this is just stupid example).

In fact, this would be a big plus for ruby, too. We could say then to our
c++/java friends that their ++ is welcome here, though it would just be
icing on the cake; ruby's oo is the meat.

Anyway, what do we lose. It's just sugar/icing, or salt? ;-)

> 
> Because Ruby has such good support for iterators, there is 
> actually very little need for explicit increment/decrement 
> operators.  The following statements are the Ruby equivalents 
> of plain 'for loops' and array iteration (the most common use 
> of x++ in other languages):
> 
>   10.times do action end
>   array.each do |x| action(x) end
> 
> Beware that these are not actually errors in Ruby.  They will 
> be parsed according to their context, so
>   x++         # incomplete statement (x + +what?)
>   array[x++]  # parse error
>   ++x         # +(+x) == x
>   --x         # -(-x) == x
>   array[++x]  # -> array[x]
> 

Currently, I am converting a perl program to ruby and it pains me since it
has a lot of the form:

if cond1
   ++x
   ++y
   ++z
end

if cond2
   ++a
   ++b
   ++c
   ++x
end

see http://jimsun.linxnet.com/downloads/pflogsumm-1.0.3.pl for the original.


> Gavin

Many thanks,
-botp