From: Rudolf Polzer <AntiATField_adsgohere@...>
Date: 2002-09-27T06:37:23+09:00
Subject: Ruby - common pitfalls?

Is there a list of common pitfalls beginners in this language should
watch out for? I noticed (I just started with Ruby and it has almost
replaced Perl):


- the if syntax. Pascal-style if is supported (and one is tempted to use
  it instead of the also supported C-style if since parantheses aren't
  easy to enter on most keyboards), but comparisons have to be written
  in C style. Therefore this happened to me more than once:

    if foo = nil then
      # ...
    end

  It's getting even worse because nil is named 'nil', like it is in
  Pascal.

  The C-style syntax is:

    if (foo == nil)
      # ...
    end

  and works perfectly. If only ( and ) were accessible without using the
  shift key...

  
- accessing one character in a string.

  s[3] does not do what most programmers would expect:
    it returns a *number*. JavaScript is cleaner in this thing - there
    are both .charAt () and .charCodeAt (). IMHO s[n] should return the
    character as a string of length one, not the value - but now it's
    too late to change this. The current meaning is not bad, it's just
    unusual.
  s[3, 1] is to be used instead.


- a %= b versus %=...=. A syntax highlighter gets into big trouble when
  seeing this construct. Nothing really seriuos, but I already had to
  insert "useless" comments to fix vim's highlighting - which is unable
  to correctly highlight if-then-end expressions. Perhaps it would help
  to deprecate %=...= as string separator (any other character could be
  used with less problems).


BTW: what about this extension:

  a, b += c, d

which would be equivalent to

  a += c
  b += d

and perfectly accepts list arguments:

  *a += *b

Maybe even

  *a = *b + *c

would be possible? Or perhaps instead:

  a.zipWith! (b) do |x, y| x + y end # slightly resembling Haskell
  a = b.zipWith (c) do |x, y| x + y end

which is a bit more verbose, but can be done with the current syntax.

Another idea for the above thing: an ArithArray class that is nearly
identical to the normal Array with one exception: the arithmetic and
logical operators work element-wise with the original meaning (so even
== would return a new array of true or false values).
  
-- 
[mpg123d] Just playing: .../01 cruel angel's thesis - director's edit - -ayanami-.mp3

Shinu no wa iya. Shinu no wa iya. Shinu no wa iya. Shinu no wa iya.
     [Asuka in Neon Genesis Evangelion - english: "I don't want to die",