Class: Loquacious::Undefined

Inherits:
Object
  • Object
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

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key) ⇒ Undefined

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

#method_missing(method, *args, &block) ⇒ Object

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.



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# 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

.io ⇒ Object

Returns the value of attribute io.



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

def io
  @io
end

Class Method Details

.warn(key) ⇒ Object

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



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# 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

#nil? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/loquacious/undefined.rb', line 70

def nil?() true; end

#respond_to_missing?(id, priv = false) ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/loquacious/undefined.rb', line 76

def respond_to_missing?( id, priv = false ) id != :call; end