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 292

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 304

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 232

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 260

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 369

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

#=~(other) ⇒ Object

:nodoc:



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# File 'lib/amazon/aws.rb', line 374

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 445

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 330

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 510

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 339

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 396

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 384

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 424

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 364

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 346

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 453

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