Class: LanGrove::ClassLoader

Inherits:
Object
  • Object
show all
Defined in:
lib/langrove/ext/class_loader.rb

Class Method Summary collapse

Class Method Details

.create(class_config, logger = nil) ⇒ Object

Raises:



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# File 'lib/langrove/ext/class_loader.rb', line 8

def self.create( class_config, logger = nil )
  
  logger.info( "#{self} is loading Class with #{class_config.inspect}" ) unless logger.nil?
  
  #
  # When <config> = {
  # 
  #   :module => 'ModuleName'
  #   :class  => 'ClassName'
  #
  # }
  #
  # Then this will return the constantized
  # definition instance of ClassName as 
  # loaded from the F1RST found .rb file
  # according to:
  # 
  # - lib/module_name/class_name.rb
  # - langrove/module_name/class_name.rb
  #
  # Which then facilitates the following
  # construct:
  #
  # planet = ClassLoader.create(
  # 
  #    :module => 'Planet',
  #    :class  => 'Mercury'
  #
  # ).new( *initializer_parameters )
  #
  
  raise ClassLoaderException.new( 
  
    "class_config requires :module" 
    
  ) unless class_config.has_key? :module
  
  raise ClassLoaderException.new( 
  
    "class_config requires :class" 
    
  ) unless class_config.has_key? :class
  
  
  module_name = class_config[:module]
  class_name  = class_config[:class]
  
  
  #
  # SIGNIFICANT DECISION
  #
  # - Late binding to the extent of also calling
  #   to require the actual class.rb file could 
  #   potentially be avoided by
  # 
  #    << using this layer in the abstraction >>
  #
  #   to do the necessary requiring for the specific
  #   daemon being spawned.
  #
  # - Obviously there are downsides to eval...
  #
  # - But there are upsides to having this layer
  #   totally aliteral - it leaves the window open
  #   to the later posibility of collecting the class
  #   definition itself from across the network. 
  #
  # 
  #   Which was the cental purpose behind daemons
  #   by configuration in the first place.
  #
  #   Taking latebinding to a whole new level...
  #
  
  
  #
  # First try local implementation root
  #
  
  exception = nil
  
  location = nil
  
  begin
    
    location = "#{module_name.underscore}/#{class_name.underscore}"
    
    eval "require '#{location}'"
    
    return Object.const_get( module_name ).const_get( class_name )
    
  rescue LoadError => e
    
    exception = e
    
    logger.error "Missing class definition in lib/#{location}.rb" unless logger.nil?
    
  #rescue Exception => e 
  #  
  #  #
  #  # Incase of more... (discovery phase)
  #  #
  #
  
    
  end
  
  #
  # Fall back to langrove gem lib
  #
  
  begin
    
    path = File.expand_path('../../',  __FILE__)
    
    location = "#{path}/#{module_name.underscore}/#{class_name.underscore}"
    
    eval "require '#{location}'"
    
    return LanGrove.const_get( module_name ).const_get( class_name )
    
  rescue Exception => e
    
    #
    # Raise from the original exception to
    # inform the local implementation
    # it is missing a module/class .rb
    # "no such file 'module/class"
    #
    # And not confuse the issue by raising
    # "no such file 'langrove/module/class"
    #
    raise ClassLoaderException.new "#{exception.message}.rb"
    
  end
  
end