Class: Loquacious::Undefined

Inherits:

Object

Object
Loquacious::Undefined

show all

Defined in:

lib/loquacious/undefined.rb

Overview

Represents an undefined configuration value. An undefined value is assigned to each configuration propery by default. Any method can be invoked on an undefined value, and a warning message will be printed to the IO stream (defaulting to $stderr).

The purpose of this class is to provide the user with a helpful message that the configuration values they are trying to use have not been setup correctly.

Class Attribute Summary (collapse)

+ (Object) io

Returns the value of attribute io.

Class Method Summary (collapse)

+ (Object) warn(key)

Write a warning message to the Undefined class IO stream.

Instance Method Summary (collapse)

- (Undefined) initialize(key) constructor

Creates a new undefined value returned from the lookup key in some configuration object.
- (Object) method_missing(method, *args, &block)

For every method invoked on an undefined object, generate a warning message describing the undefined value and the method that was called.
- (Boolean) nil?

An undefined value acts like a nil in that it has no value of its own.
- (Boolean) respond_to_missing?(id, priv = false)

We can respond to any method except :call.

Constructor Details

- (`Undefined`) initialize(key)

Creates a new undefined value returned from the lookup key in some configuration object. The key is used to alert the user where the undefined value came from.



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# File 'lib/loquacious/undefined.rb', line 63

def initialize( key )
  @key = Kernel.Array(key)
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

- (`Object`) method_missing(method, *args, &block)

For every method invoked on an undefined object, generate a warning message describing the undefined value and the method that was called.

Returns a new undefined object with the most recent method included in the key name.

# File 'lib/loquacious/undefined.rb', line 84

def method_missing( method, *args, &block )
  key = @key.dup << method.to_s
  Undefined.warn key
  return Undefined.new(key)
end

Class Attribute Details

+ (`Object`) io

Returns the value of attribute io



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# File 'lib/loquacious/undefined.rb', line 37

def io
  @io
end

Class Method Details

+ (`Object`) warn(key)

Write a warning message to the Undefined class IO stream. By default, this IO stream is set to the Ruby $stderr output.

# File 'lib/loquacious/undefined.rb', line 42

def warn( key )
  if @first_time
    @io.puts <<-__
---------------------------------------------------------------------------
The Loquacious configuration system has detected that one or moe
settings have an undefined value. An attempt is being made to reference
sub-properties of these undefined settings. Messages will follow containing
information about the undefined properties.
---------------------------------------------------------------------------
    __
    @first_time = false
  end

  @io.puts "Access to undefined value #{key.first.inspect}: #{key.join('.')}"
end

Instance Method Details

- (`Boolean`) nil?

An undefined value acts like a nil in that it has no value of its own. This method always returns true.

Returns:

(Boolean)

70	# File 'lib/loquacious/undefined.rb', line 70 def nil?() true; end

- (`Boolean`) respond_to_missing?(id, priv = false)

We can respond to any method except :call. The call method is reserved for Procs and lambdas, and it is used internally by loquacious for lazy evaluation of configuration parameters.