==================
Ruby
==================

.. note:: This information is very rough, it's mostly my notes about what is 
    different about Ruby syntax compared to similar modern interpreted 
    pan-paradigm languages like Python.

A unique intro to ruby is `"Why's Poignant Guide to Ruby"`__, a web-comic-y 
short free online book by why the luck stiff. The more serious reference is 
the "pickax" book.

__ http://poignantguide.net/

Blocks
---------
Blocks of code can be passed to functions, making ruby code more of a first
order data type.

Ranges 
----------

>>> 2..7                # => 2..7
>>> (2..7).to_a         # => [2, 3, 4, 5, 6, 7]
>>> (2...7).to_a        # => [2, 3, 4, 5, 6]
>>> ('e'..'h').to_a     # => ["e", "f", "g", "h"]

Control Structures
--------------------
Can use ``if`` after a statement::

>>> a = c if c > b

Along with the usual ``break`` and ``next``, there is ``redo`` which redoes
the current loop (initial conditions may have been changed).


Boolean Operators
--------------------
Anything that is not ``nill`` or ``false`` is true. To force interpretation
as boolean, use ``!!`` (not not)::

>>> !!(nil)     # => false
>>> !!(true)    # => true 
>>> !!('')      # => true 
>>> !!(0)       # => true 
>>> !!({})      # => true 


Misc
----------------
Can use nasty Perl style regular expression stuff::

>>> re1 = /\d+/
>>> "There are 5 kilos of chunky bacon on the table!" =~ re1 # => 10, the index
>>> $~ # =>         #<MatchData:0xb7c36754> 
>>> $~.pre_hash     # => "There are "

Also $1, $2, etc.

The "splat operator", '*', either collects or expands extra arguments depending
on syntax (I think this is kind of icky)::

>>> a, b = 1, 2, 3, 4       # a=1, b=2
>>> a, *b = 1, 2, 3, 4      # a=1, b=[2,3,4] 
>>> c, d = 5, [6, 7, 8]     # c=5, d=[6,7,8]
>>> c, d = 5, *[6, 7, 8]    # c=5, b=6