Attributes-3.2.0

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 N. 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

 #
 # also not that attribute(s) works as well for objects as classes
 #
   o = Object.new
   o.attribute 'answer' => 42
   p o.answer

~ > ruby samples/a.rb

 42
 "forty-two"
 42

<========< 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
     attribute(:b){ 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"

<========< samples/e.rb >========>

~ > cat samples/e.rb

 #
 # my favourite element of attributes is that getters can also be 

setters.
# this allows incredibly clean looking code like
#
require ‘attributes’

   class Config
     attributes %w( host port)
     def initialize(&block) instance_eval &block end
   end

   conf = Config.new{
     host 'codeforpeople.org'

     port 80
   }

   p conf

~ > ruby samples/e.rb

 #<Config:0xb75cc6bc @port=80, @host="codeforpeople.org">

enjoy.

-a

[email protected]domain.invalid wrote:

NAME

attributes.rb

with :

~/Desktop%> sudo gem install attributes

i get :
ERROR: Error installing gem attributes[.gem]: undefined method
`required_ruby_version’ for nil:NilClass

over MacOS X 1O.4.8

and :

ruby -version
ruby 1.8.5 (2006-08-25) [powerpc-darwin8.8.0]

and :
~/Desktop%> gem -v
0.9.0

Une Bévue wrote:

ERROR: Error installing gem attributes[.gem]: undefined method
`required_ruby_version’ for nil:NilClass

I’m also on Mac OS X 10.4.8, and it works for me, but with an older
version of gems:

Slim:~ gavinkistner$ ruby -v && gem -v
ruby 1.8.5 (2006-08-25) [powerpc-darwin8.7.0]
0.8.11
Slim:~ gavinkistner$ sudo gem install attributes
Password:
Attempting local installation of ‘attributes’
Local gem file not found: attributes*.gem
Attempting remote installation of ‘attributes’
Updating Gem source index for: http://gems.rubyforge.org
Successfully installed attributes-3.2.0

In fact, I can’t seem to upgrade gems (but let’s not hijack the thread
with that bit of info).

Phrogz [email protected] wrote:

In fact, I can’t seem to upgrade gems (but let’s not hijack the thread
with that bit of info).

i can’y downgrade )))

but i think i could install it “manually” by myself, don’t worry :wink:

On 17-Oct-06, at 7:00 AM, Une Bévue wrote:

and :
~/Desktop%> gem -v
0.9.0

No problem here and I have almost the same configuration (I have i686-
darwin8.8.1)

Cheers,
Bob


Bob H. – blogs at <http://www.recursive.ca/
hutch/>
Recursive Design Inc. – http://www.recursive.ca/
Raconteur – http://www.raconteur.info/
xampl for Ruby – http://rubyforge.org/projects/xampl/

[email protected] wrote:

try to get a backtrace and send to the gem team.

i’d like (i’m also a gem modest designer) to help the gem community but
i don’t know how to do a backtrace…

i get about the same prob attempting a remote install :

~/Desktop%> sudo gem install -r attributes
Password:
Bulk updating Gem source index for: http://gems.rubyforge.org
ERROR: While executing gem … (NoMethodError)
undefined method `each’ for #Object:0x67518d0

On Tue, 17 Oct 2006, [ISO-8859-1] Une Bévue wrote:

and :
~/Desktop%> gem -v
0.9.0

sorry, must be on your end mac/ruby/gem:

harp:~ > gem install attributes
[]
Attempting local installation of ‘attributes’
Local gem file not found: attributes*.gem
Attempting remote installation of ‘attributes’
Updating Gem source index for: http://gems.rubyforge.org
Successfully installed attributes-3.2.0

harp:~ > ruby -v
ruby 1.8.4 (2005-12-01) [i686-linux]

harp:~ > gem -v
0.8.11

try to get a backtrace and send to the gem team.

cheers.

-a

On Wed, 18 Oct 2006, [ISO-8859-1] Une Bévue wrote:

i get about the same prob attempting a remote install :

~/Desktop%> sudo gem install -r attributes
Password:
Bulk updating Gem source index for: http://gems.rubyforge.org
ERROR: While executing gem … (NoMethodError)
undefined method `each’ for #Object:0x67518d0

try

~/Desktop%> sudo gem --debug install -r attributes

-a

This forum is not affiliated to the Ruby language, Ruby on Rails framework, nor any Ruby applications discussed here.

| Privacy Policy | Terms of Service | Remote Ruby Jobs