Class: Amazon::AWS::AWSObject

Inherits:
Object
  • Object
show all
Includes:
REXML
Defined in:
lib/amazon/aws.rb

Overview

Everything returned by AWS is an AWSObject.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(op = nil) ⇒ AWSObject

Returns a new instance of AWSObject.



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# File 'lib/amazon/aws.rb', line 261

def initialize(op=nil)
	# The name of this instance variable must never clash with the
	# uncamelised name of an Amazon tag.
	#
	# This is used to store the REXML::Text value of an element, which
	# exists only when the element contains no children.
	#
	@__val__ = nil
	@__op__ = op if op
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method, *params) ⇒ Object (private) 



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# File 'lib/amazon/aws.rb', line 273

def method_missing(method, *params)
	iv = '@' + method.id2name

	if instance_variables.include?( iv )
	  instance_variable_get( iv )
	elsif instance_variables.include?( iv.to_sym )

	  # Ruby 1.9 Object#instance_variables method returns Array of Symbol,
	  # not String.
	  #
	  instance_variable_get( iv.to_sym )
	else
	  nil
	end
end

Class Method Details

.load(io) ⇒ Object

This method can be used to load AWSObject data previously serialised by Marshal.dump.

Example:

File.open( 'aws.dat' ) { |f| Amazon::AWS::AWSObject.load( f ) }

Marshal.load cannot be used directly, because subclasses of AWSObject are dynamically defined as needed when AWS XML responses are parsed.

Later attempts to load objects instantiated from these classes cause a problem for Marshal, because it knows nothing of classes that were dynamically defined by a separate process.



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# File 'lib/amazon/aws.rb', line 201

def AWSObject.load(io)
	begin
	  Marshal.load( io )
	rescue ArgumentError => ex
	  m = ex.to_s.match( /Amazon::AWS::AWSObject::([^ ]+)/ )
	  const_set( m[1], Class.new( AWSObject ) )

	  io.rewind
	  retry
	end
end

.yaml_load(io) ⇒ Object

This method can be used to load AWSObject data previously serialised by YAML.dump.

Example:

File.open( 'aws.yaml' ) { |f| Amazon::AWS::AWSObject.yaml_load( f ) }

The standard YAML.load cannot be used directly, because subclasses of AWSObject are dynamically defined as needed when AWS XML responses are parsed.

Later attempts to load objects instantiated from these classes cause a problem for YAML, because it knows nothing of classes that were dynamically defined by a separate process.



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# File 'lib/amazon/aws.rb', line 229

def AWSObject.yaml_load(io)
  io.each do |line|
    
	  # File data is external, so it's deemed unsafe when $SAFE > 0, which
	  # is the case with mod_ruby, for example, where $SAFE == 1.
	  #
	  # YAML data isn't eval'ed or anything dangerous like that, so we
	  # consider it safe to untaint it. If we don't, mod_ruby will complain
	  # when Module#const_defined? is invoked a few lines down from here.
	  #
	  line.untaint
	  
	  m = line.match( /Amazon::AWS::AWSObject::([^ ]+)/ )
	  if m
	    cl_name = [ m[1] ]
	  
	    # Module#const_defined? takes 2 parameters in Ruby 1.9.
	    #
	    cl_name << false if Object.method( :const_defined? ).arity == -1
	  
	    unless AWSObject.const_defined?( *cl_name )
 AWSObject.const_set( m[1], Class.new( AWSObject ) )
	    end
	  
	  end
	end
    
	io.rewind
	YAML.load( io )
end

Instance Method Details

#==(other) ⇒ Object

:nodoc:



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# File 'lib/amazon/aws.rb', line 338

def ==(other)  # :nodoc:
  @__val__.to_s == other
end

#=~(other) ⇒ Object

:nodoc:



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# File 'lib/amazon/aws.rb', line 343

def =~(other)  # :nodoc:
	@__val__.to_s =~ other
end

#[](key) ⇒ Object

Fake the appearance of an AWSObject as a hash. key should be any attribute of the object and can be a String, Symbol or anything else that can be converted to a String with to_s.



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# File 'lib/amazon/aws.rb', line 414

def [](key)
	instance_variable_get( "@#{key}" )
end

#each ⇒ Object Also known as: each_property

Iterator method for cycling through an object’s properties and values.



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# File 'lib/amazon/aws.rb', line 299

def each  # :yields: property, value
	self.properties.each do |iv|
	  yield iv, instance_variable_get( "@#{iv}" )
	end
end

#get(discount = nil) ⇒ Object

For objects of class AWSObject::.*Image, fetch the image in question, optionally overlaying a discount icon for the percentage amount of discount to the image.



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# File 'lib/amazon/aws.rb', line 479

def get(discount=nil)
	if self.class.to_s =~ /Image$/ && @url
    url = URI.parse( @url[0] )
    url.path.sub!( /(\.\d\d\._)/, "\\1PE#{discount}" ) if discount

	  # FIXME: All HTTP in Ruby/AWS should go through the same method.
	  #
    Net::HTTP.start( url.host, url.port ) do |http|
	    http.get( url.path )
	  end.body

	else
	  nil
	end
end

#inspect ⇒ Object

:nodoc:



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# File 'lib/amazon/aws.rb', line 308

def inspect  # :nodoc:
	remove_val if instance_variable_defined?( :@__val__ ) && @__val__.nil?
	str = super
	str.sub( /@__val__=/, 'value=' ) if str
end

#kernel ⇒ Object

Provide a shortcut down to the data likely to be of most interest. This method is experimental and may be removed.



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# File 'lib/amazon/aws.rb', line 365

def kernel  # :nodoc: 
	# E.g. Amazon::AWS::SellerListingLookup -> seller_listing_lookup
	#
	stub = Amazon.uncamelise( @__op__.class.to_s.sub( /^.+::/, '' ) )

	# E.g. seller_listing_response
	#
	level1 = stub + '_response'

	# E.g. seller_listing
	#
	level3 = stub.sub( /_[^_]+$/, '' )

	# E.g. seller_listings
	#
	level2 = level3 + 's'

	# E.g.
	# seller_listing_search_response[0].seller_listings[0].seller_listing
	#
	self.instance_variable_get( "@#{level1}" )[0].
instance_variable_get( "@#{level2}" )[0].
instance_variable_get( "@#{level3}" )
end

#properties ⇒ Object

This alias makes the ability to determine an AWSObject’s properties a little more intuitive. It’s pretty much just an alias for the inherited Object#instance_variables method, with a little tidying.



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# File 'lib/amazon/aws.rb', line 353

def properties
	# Make sure we remove the leading @.
	#
	iv = instance_variables.collect { |v| v = v[1..-1] }
	iv.delete( '__val__' )
	iv
end

#to_h ⇒ Object

Convert an AWSObject to a Hash.



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# File 'lib/amazon/aws.rb', line 393

def to_h
	hash = {}

	each do |iv, value|
	  if value.is_a? AWSObject
	    hash[iv] = value.to_h
	  elsif value.is_a?( AWSArray ) && value.size == 1
	    hash[iv] = value[0]
	  else
	    hash[iv] = value
	  end
	end

	hash
end

#to_i ⇒ Object

:nodoc:



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# File 'lib/amazon/aws.rb', line 333

def to_i	# :nodoc:
	@__val__.to_i
end

#to_s ⇒ Object Also known as: to_str

:nodoc:



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# File 'lib/amazon/aws.rb', line 315

def to_s	# :nodoc:
	if instance_variable_defined?( :@__val__ )
	  return @__val__ if @__val__.is_a?( String )
	  remove_val
	end

	string = ''

	# Assemble the object's details.
	#
	each { |iv, value| string << "%s = %s\n" % [ iv, value ] }

	string
end

#walk(node) ⇒ Object

Recursively walk through an XML tree, starting from node. This is called internally and is not intended for user code.



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# File 'lib/amazon/aws.rb', line 422

def walk(node)  # :nodoc:
    
	if node.instance_of?( REXML::Document )
	  walk( node.root )
    
	elsif node.instance_of?( REXML::Element )
	  name = Amazon.uncamelise( node.name )
    
	  cl_name = [ node.name ]

	  # Module#const_defined? takes 2 parameters in Ruby 1.9.
	  #
	  cl_name << false if Object.method( :const_defined? ).arity == -1

	  # Create a class for the new element type unless it already exists.
	  #
	  unless AWS::AWSObject.const_defined?( *cl_name )
	    cl = AWS::AWSObject.const_set( node.name, Class.new( AWSObject ) )

	    # Give it an accessor for @attrib.
	    #
	    cl.send( :attr_accessor, :attrib )
	  end
    
	  # Instantiate an object in the newly created class.
	  #
	  obj = AWS::AWSObject.const_get( node.name ).new

	  sym_name = "@#{name}".to_sym
    
	  if instance_variable_defined?( sym_name)
   instance_variable_set( sym_name,
     instance_variable_get( sym_name ) << obj )
	  else
	    instance_variable_set( sym_name, AWSArray.new( [ obj ] ) )
	  end
    
	  if node.has_attributes?
	    obj.attrib = {}
	    node.attributes.each_pair do |a_name, a_value|
 obj.attrib[a_name.downcase] =
		a_value.to_s.sub( /^#{a_name}=/, '' )
	    end
	  end

	  node.children.each { |child| obj.walk( child ) }
    
	else # REXML::Text
	  @__val__ = node.to_s
	end
end