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.



250
251
252
253
254
255
256
257
258
259
 
# File 'lib/amazon/aws.rb', line 250

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) 



262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
 
# File 'lib/amazon/aws.rb', line 262

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.



190
191
192
193
194
195
196
197
198
199
200
 
# File 'lib/amazon/aws.rb', line 190

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.



218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
 
# File 'lib/amazon/aws.rb', line 218

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:



327
328
329
 
# File 'lib/amazon/aws.rb', line 327

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

#=~(other) ⇒ Object

:nodoc:



332
333
334
 
# File 'lib/amazon/aws.rb', line 332

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.



403
404
405
 
# File 'lib/amazon/aws.rb', line 403

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.



288
289
290
291
292
 
# File 'lib/amazon/aws.rb', line 288

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.



468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
 
# File 'lib/amazon/aws.rb', line 468

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:



297
298
299
300
301
 
# File 'lib/amazon/aws.rb', line 297

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.



354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
 
# File 'lib/amazon/aws.rb', line 354

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.



342
343
344
345
346
347
348
 
# File 'lib/amazon/aws.rb', line 342

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.



382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
 
# File 'lib/amazon/aws.rb', line 382

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:



322
323
324
 
# File 'lib/amazon/aws.rb', line 322

def to_i  # :nodoc:
  @__val__.to_i
end

#to_s ⇒ Object Also known as: to_str

:nodoc:



304
305
306
307
308
309
310
311
312
313
314
315
316
317
 
# File 'lib/amazon/aws.rb', line 304

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.



411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
 
# File 'lib/amazon/aws.rb', line 411

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