From: Gavin Sinclair <gsinclair@...>
Date: 2002-12-01T23:07:25+09:00
Subject: [FAQ] What do some of Ruby's symbols mean?

This could do with some community input before going to the FAQ.  The format
will be different but I just wanted to bang out some content.  I haven't even
checked if there is a question like this.

Can anyone think of a question title that does't create confusion with :name
symbols?

---

Q: What do some of Ruby's symbols mean?

A:

This question is about non-aplhanumeric characters in Ruby code, not about
*symbols* like :name.  For those, see [appropriate link].  Actual explanations
of the concepts behind them is beyond the scope of this answer.

<= < != == > >>
   Relational operators, as per most other computer languages.  Are often
   redefined for use with various classes.

+ - * / %
   Common arithmetic operators.  Some are defined also for String, Array
   and others.

===
   Case comparison operator.  Used to select branches in case statements.

<
   Class inheritance, as in
     class Car < Vehicle
     end

<<
   Funny class inheritance; see [appropriate link] for a rationale.  Also
   commonly used as a method for appending (e.g. Array and String).

.. ...
   Range definers, as in 0...10 and "a".."z"

:
   Symbol definer, as in :name, where :name.to_s == "name".  See [a/l].
   See next item also.

?:
   Ternary decision operator, as in C.  For example:
     iq = (position == MANAGER) ? LOW : HIGH

{} =>
   Hash definition, as in
     numstr = { 1 => "one", 2 => "two", ... }

[]
   Array definition, as in
     ndays = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ]

%w[]
   String-Array converter, as in
     dayabbrev = %w[Sun Mon Tue Wed Thu Fri Sat]
     dayabbrev == ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"]

//
   Regular expression definition, as in
     date_re = /(\d\d\d\d)-(\d\d)-(\d\d)/
     y, m, d = date_re.match("2002-12-01")[1..3]

?!
   Suffixes for methods (optional, of course).  In general:
     method!   changes the object (e.g. String.gsub!)
     method?   returns boolean    (e.g. Array.empty?)