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