[ANN] attributes-3.0.0

[ara.t.howard]

NAME

attributes.rb

URIS

http://rubyforge.org/projects/codeforpeople/
http://codeforpeople.com/lib/ruby

SYNOPSIS

attributes.rb provides an attr_* like method will several user friendly
additions. attributes.rb is similar to the traits.rb package but sacrafices
a few features for simplicity of implementation: attributes.rb is only 42
lines of code.

the implimentation of attributes.rb borrows many of the best ideas from the
metakoans.rb ruby quiz

http://www.rubyquiz.com/quiz67.html

in particular the solutions of Christian Neukirchen and Florian Gross.

SAMPLES

<========< samples/a.rb >========>

~ > cat samples/a.rb

#
# basic usage is like attr, but note that attribute defines three methods,
# getter, setter, and query
#
require 'attributes'

class C
attribute 'a'
end

c = C.new

c.a = 42 # setter
p c.a # getter
p 'forty-two' if c.a? # query

~ > ruby samples/a.rb

42
"forty-two"


<========< samples/b.rb >========>

~ > cat samples/b.rb

#
# default values may be given either directly or as a block which will be
# evaluated in the context of self. in both cases (value or block) the
# default is set only once and only if needed - it's a lazy evaluation.
#
require 'attributes'

class C
attribute :a => 42
attributeb){ Float a }
end

c = C.new

p c.a
p c.b

~ > ruby samples/b.rb

42
42.0


<========< samples/c.rb >========>

~ > cat samples/c.rb

#
# multiple values may by given, plain names and key/val pairs may be mixed.
#
require 'attributes'

class C
attributes 'x', 'y' => 0b101000, 'z' => 0b10
end

c = C.new
c.x = c.y + c.z
p c.x


~ > ruby samples/c.rb

42


<========< samples/d.rb >========>

~ > cat samples/d.rb

#
# a nice feature is that all attributes are enumerated in the class. this,
# combined with the fact that the getter method is defined so as to delegate
# to the setter when an argument is given, means bulk initialization and/or
# attribute traversal is very easy.
#
require 'attributes'

class C
attributes %w( x y z )

def attributes
self.class.attributes
end

def initialize
attributes.each_with_index{|a,i| send a, i}
end

def to_hash
attributes.inject({}){|h,a| h.update a => send(a)}
end

def inspect
to_hash.inspect
end
end

c = C.new
p c.attributes
p c

c.x 'forty-two'
p c.x

~ > ruby samples/d.rb

["x", "y", "z"]
{"x"=>0, "y"=>1, "z"=>2}
"forty-two"


-a