Class: Yacl::Define::Plan

Inherits:
Object
  • Object
show all
Defined in:
lib/yacl/define/plan.rb

Overview

Public: The Plan is the order an method by which the Properties of your application are loaded and looked up. This is a base class from which you will define your Property lookups.

Example:

class MyPlan < Yacl::Define::Plan
  try MyApp::Cli::Parser
  try Yacl::Loader::Env, :prefix => 'MY_APP'
  try Yacl::Loader::YamlDir, :parameter => 'config.dir'
  try MyApp::Defaults

  on_error do |exception|
    $stderr.puts "ERROR: #{exception}"
    $stderr.puts "Try --help for help"
    exit 1
  end
end

This creates a class MyPlan that when utilized by a Runner loads properties in the following cascading order:

1) Commandline is parsed and converted to Properties, these have the highest

priority

2) The environemtn variables are used, only those that start with ‘MY_APP’

as the variable prefix. These have the 2nd higest priority

3) A configuration directory is loaded, using the ‘config.dir’ parameter

that comes from either (1) or (2). Properties found in this config dir
hve the 3rd highest priority

4) Built in defaults if the property is not found any any of the previous

locations.

Defined Under Namespace

Classes: Error, Item

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(params = {}) ⇒ Plan

Public: Create a new instance of the Plan. This should be invoked via #super in a child class.



137
138
139
140
141
142
143
144
145
146
 
# File 'lib/yacl/define/plan.rb', line 137

def initialize( params = {} )
  initial_properties = params[:initial_properties] || Yacl::Properties.new
  @properties = load_properties( initial_properties, params, items )
rescue Yacl::Error => ye
  if self.class.has_on_error? then
    self.class.on_error.call( ye )
  else
    raise ye
  end
end

Instance Attribute Details

#properties ⇒ Object (readonly)

Public: Return the Properties instance that results from instantiating the Plan.

Returns an Properties instance.



132
133
134
 
# File 'lib/yacl/define/plan.rb', line 132

def properties
  @properties
end

Class Method Details

.has_on_error? ⇒ Boolean

Internal: Test to see if this class has an on_error callable defined.

Returns true or false if the on_error is defined.

Returns:

  • (Boolean) 


108
109
110
 
# File 'lib/yacl/define/plan.rb', line 108

def has_on_error?
  defined? @on_error
end

.items ⇒ Object

Internal: Return the array of Items that are used in the child class definition.

Returns: an Array of Items



116
117
118
 
# File 'lib/yacl/define/plan.rb', line 116

def items
  @items ||= []
end

.on_error(callable = nil, &block) ⇒ Object

Public: Define a callable to be invoked should an error happen while loading the properties of your application.

callable - the Callable to be invoked.

Example:

on_error( Proc.new{ fail "kaboom!" } )

on_error do
  raise "Kaboom!"
end

Return the callable if no parameters are given and the callable is defined.

Raises an error if no parameters are given and the callable is NOT defined.



93
94
95
96
97
98
99
100
101
102
103
 
# File 'lib/yacl/define/plan.rb', line 93

def on_error( callable = nil, &block )
  if callable then
    @on_error = callable
  elsif block_given?
    @on_error =  block
  elsif defined? @on_error
    return @on_error
  else
    raise Error, "on_error requires the use of a callable or a block"
  end
end

.try(klass, options = {}) ⇒ Object

Public: Add the given Loader child class or Loader duck-type class to the definition of the Plan.

klass - A Class that implements the Loader API. options - A Hash that will be passed to klass.new() when the klass is

initialized

Example:

try Yacl::Loader::YamlDir, :parameter => 'config.dir'

Returns nothing.



70
71
72
 
# File 'lib/yacl/define/plan.rb', line 70

def try( klass , options = {} )
  items << Item.new( klass, options )
end

Instance Method Details

#items ⇒ Object

Internal: Return the array of Items defined for this class

Returns an Array of Items.



124
125
126
 
# File 'lib/yacl/define/plan.rb', line 124

def items
  self.class.items
end