configuration

= configuration.rb pure ruby scoped configuration files

== Description configuration.rb provides a mechanism for configuring ruby programs with ruby configuration files. a configuration.rb file, for example 'config/app.rb', can be written simply as

Configuration.for('app') { key 'value' foo 'bar' port 42 }

and loaded via the normal ruby require/load mechanism

Kernel.load 'config/app.rb'

or with a slightly augmented loading mechnanism which simply searches an extra set of paths in addition to the standard ones

Configuration.path = %w( config configuration )

Configuration.load 'app'

configurations are completely open

Configuration.for('app') { object_id 'very open' }

support arbitrarily nested values

Configuration.for('app') { a { b { c { d 42 } } } }

c = Configuration.for 'app'

p c.a.b.c.d #=> 42

allow POLS scoped lookup of vars

Configuration.for('config') { outer 'bar'

inner {
  value 42
}

}

c = Configuration.for 'config'

p c.outer #=> 'bar' p c.inner.value #=> 42 p c.inner.outer #=> 'bar'

allow default values

default = Configuration.for( 'default' ) { a 1 b 2 }

c = Configuration.for( 'config', default ) { a 10 }

p c.a #=> 10 p c.b #=> 2

and not a whole lot else - configuration.rb is s very small library consisting of one file and < 150 loc

== Samples

=== samples/a.rb ~ > cat samples/a.rb

#
# basic usage is quite, simple, load the config and use it's values.  the
# config syntax is fairly obvious, i think, but note that it *is* ruby and any
# ruby can be included.  also note that each config is named, allowing
# multiple configs to be places in one file
#
  require 'configuration'

  c = Configuration.load 'a'

  p c.a + c.b - c.c

~ > ruby samples/a.rb

42

=== samples/b.rb ~ > cat samples/b.rb

#
# configuration.rb supports a very natural nesting syntax.  note how values
# are scoped in a POLS fashion
#
  require 'configuration'

  c = Configuration.for 'b'

  p c.www.url
  p c.db.url
  p c.mail.url

~ > ruby samples/b.rb

"http://codeforpeople.com:80"
"db://codeforpeople.com:5342"
"mail://gmail.com:25"

=== samples/c.rb ~ > cat samples/c.rb

#
# configuration.rb let's you keep code very dry.
#

  require 'configuration'

  Configuration.load 'c'

  p Configuration.for('development').db
  p Configuration.for('production').db
  p Configuration.for('testing').db

~ > ruby samples/c.rb

"db/development"
"db/production"
"db/testing"

=== samples/d.rb ~ > cat samples/d.rb

#
# configuration.rb makes use of an external blank slate dsl, this means that
# you Configuration objects do, in fact, have all built-in ruby methods such
# as #inspect, etc, *unless* you configure over the top of them.  the effect
# is a configuration object that behaves like a nice ruby object, but which
# allows *any* key to be configured
#
  require 'configuration'

  c = Configuration.for 'd'

  p c.object_id
  p c.inspect
  p c.p

~ > ruby samples/d.rb

config/d.rb:2:in `object_id': wrong number of arguments (1 for 0) (ArgumentError)
  from config/d.rb:2
  from ./lib/configuration.rb:159:in `instance_eval'
  from ./lib/configuration.rb:159:in `call'
  from ./lib/configuration.rb:159:in `method_missing'
  from ./lib/configuration.rb:105:in `evaluate'
  from ./lib/configuration.rb:68:in `initialize'
  from ./lib/configuration.rb:29:in `new'
  from ./lib/configuration.rb:29:in `for'
  from config/d.rb:1
  from ./lib/configuration.rb:53:in `load'
  from ./lib/configuration.rb:53:in `load'
  from ./lib/configuration.rb:31:in `for'
  from samples/d.rb:10

=== samples/e.rb ~ > cat samples/e.rb

#
# configuration.rb uses a totally clean slate dsl for the block.  if you need
# to access base Object methods you can do this
#

  require 'configuration'

  c = Configuration.for 'e'

  p c.foo
  p c.bar
  p c.foobar

~ > ruby samples/e.rb

42
"forty-two"
42.0

=== samples/f.rb ~ > cat samples/f.rb

#
# configuration.rb let's you inherit values from another configuration.
# Like this, you keep your code very dry.
#

  require 'configuration'

  Configuration.load 'f'

  p c.a
  p c.b

~ > ruby samples/f.rb

10
2

== Author [e-mail]