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# -*- mode: ruby; ruby-indent-level: 4; tab-width: 4 -*- vim: sw=4 ts=4
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# $Id: yaml.rb 11708 2007-02-12 23:01:19Z shyouhei $
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# = yaml.rb: top-level module with methods for loading and parsing YAML documents
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# Author:: why the lucky stiff
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require 'yaml/constants'
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# YAML(tm) (rhymes with 'camel') is a
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# straightforward machine parsable data serialization format designed for
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# human readability and interaction with scripting languages such as Perl
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# and Python. YAML is optimized for data serialization, formatted
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# dumping, configuration files, log files, Internet messaging and
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# filtering. This specification describes the YAML information model and
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# serialization format. Together with the Unicode standard for characters, it
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# provides all the information necessary to understand YAML Version 1.0
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# and construct computer programs to process it.
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# See http://yaml.org/ for more information. For a quick tutorial, please
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# visit YAML In Five Minutes (http://yaml.kwiki.org/?YamlInFiveMinutes).
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# == About This Library
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# The YAML 1.0 specification outlines four stages of YAML loading and dumping.
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# This library honors all four of those stages, although data is really only
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# available to you in three stages.
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# The four stages are: native, representation, serialization, and presentation.
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# The native stage refers to data which has been loaded completely into Ruby's
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# own types. (See +YAML::load+.)
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# The representation stage means data which has been composed into
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# +YAML::BaseNode+ objects. In this stage, the document is available as a
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# tree of node objects. You can perform YPath queries and transformations
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# at this level. (See +YAML::parse+.)
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# The serialization stage happens inside the parser. The YAML parser used in
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# Ruby is called Syck. Serialized nodes are available in the extension as
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# The presentation stage is the YAML document itself. This is accessible
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# to you as a string. (See +YAML::dump+.)
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# For more information about the various information models, see Chapter
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# 3 of the YAML 1.0 Specification (http://yaml.org/spec/#id2491269).
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# The YAML module provides quick access to the most common loading (YAML::load)
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# and dumping (YAML::dump) tasks. This module also provides an API for registering
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# global types (YAML::add_domain_type).
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# A simple round-trip (load and dump) of an object.
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# test_obj = ["dogs", "cats", "badgers"]
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# yaml_obj = YAML::dump( test_obj )
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# ruby_obj = YAML::load( yaml_obj )
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# # => ["dogs", "cats", "badgers"]
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# ruby_obj == test_obj
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# To register your custom types with the global resolver, use +add_domain_type+.
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# YAML::add_domain_type( "your-site.com,2004", "widget" ) do |type, val|
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Resolver = YAML::Syck::Resolver
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DefaultResolver = YAML::Syck::DefaultResolver
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DefaultResolver.use_types_at( @@tagged_classes )
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GenericResolver = YAML::Syck::GenericResolver
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Parser = YAML::Syck::Parser
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Emitter = YAML::Syck::Emitter
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# Returns a new default parser
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def YAML.parser; Parser.new.set_resolver( YAML.resolver ); end
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# Returns a new generic parser
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def YAML.generic_parser; Parser.new.set_resolver( GenericResolver ); end
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# Returns the default resolver
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def YAML.resolver; DefaultResolver; end
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# Returns a new default emitter
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def YAML.emitter; Emitter.new.set_resolver( YAML.resolver ); end
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# Converts _obj_ to YAML and writes the YAML result to _io_.
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# File.open( 'animals.yaml', 'w' ) do |out|
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# YAML.dump( ['badger', 'elephant', 'tiger'], out )
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# If no _io_ is provided, a string containing the dumped YAML
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# YAML.dump( :locked )
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def YAML.dump( obj, io = nil )
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obj.to_yaml( io || io2 = StringIO.new )
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io || ( io2.rewind; io2.read )
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# Load a document from the current _io_ stream.
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# File.open( 'animals.yaml' ) { |yf| YAML::load( yf ) }
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# #=> ['badger', 'elephant', 'tiger']
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# Can also load from a string.
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# YAML.load( "--- :locked" )
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yp = parser.load( io )
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# Load a document from the file located at _filepath_.
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# YAML.load_file( 'animals.yaml' )
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# #=> ['badger', 'elephant', 'tiger']
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def YAML.load_file( filepath )
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File.open( filepath ) do |f|
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# Parse the first document from the current _io_ stream
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# File.open( 'animals.yaml' ) { |yf| YAML::load( yf ) }
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# #=> #<YAML::Syck::Node:0x82ccce0
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# [#<YAML::Syck::Node:0x82ccd94
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# #<YAML::Syck::Node:0x82ccd58
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# @value="elephant">,
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# #<YAML::Syck::Node:0x82ccd1c
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# Can also load from a string.
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# YAML.parse( "--- :locked" )
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# #=> #<YAML::Syck::Node:0x82edddc
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# @type_id="tag:ruby.yaml.org,2002:sym",
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# @value=":locked", @kind=:scalar>
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yp = generic_parser.load( io )
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# Parse a document from the file located at _filepath_.
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# YAML.parse_file( 'animals.yaml' )
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# #=> #<YAML::Syck::Node:0x82ccce0
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# [#<YAML::Syck::Node:0x82ccd94
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# #<YAML::Syck::Node:0x82ccd58
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# @value="elephant">,
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# #<YAML::Syck::Node:0x82ccd1c
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def YAML.parse_file( filepath )
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File.open( filepath ) do |f|
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# Calls _block_ with each consecutive document in the YAML
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# stream contained in _io_.
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# File.open( 'many-docs.yaml' ) do |yf|
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# YAML.each_document( yf ) do |ydoc|
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# ## ydoc contains the single object
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# ## from the YAML document
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def YAML.each_document( io, &block )
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yp = parser.load_documents( io, &block )
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# Calls _block_ with each consecutive document in the YAML
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# stream contained in _io_.
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# File.open( 'many-docs.yaml' ) do |yf|
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# YAML.load_documents( yf ) do |ydoc|
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# ## ydoc contains the single object
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# ## from the YAML document
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def YAML.load_documents( io, &doc_proc )
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YAML.each_document( io, &doc_proc )
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# Calls _block_ with a tree of +YAML::BaseNodes+, one tree for
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# each consecutive document in the YAML stream contained in _io_.
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# File.open( 'many-docs.yaml' ) do |yf|
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# YAML.each_node( yf ) do |ydoc|
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# ## ydoc contains a tree of nodes
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# ## from the YAML document
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def YAML.each_node( io, &doc_proc )
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yp = generic_parser.load_documents( io, &doc_proc )
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# Calls _block_ with a tree of +YAML::BaseNodes+, one tree for
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# each consecutive document in the YAML stream contained in _io_.
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# File.open( 'many-docs.yaml' ) do |yf|
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# YAML.parse_documents( yf ) do |ydoc|
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# ## ydoc contains a tree of nodes
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# ## from the YAML document
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def YAML.parse_documents( io, &doc_proc )
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YAML.each_node( io, &doc_proc )
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# Loads all documents from the current _io_ stream,
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# returning a +YAML::Stream+ object containing all
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def YAML.load_stream( io )
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parser.load_documents( io ) do |doc|
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d = YAML::Stream.new if not d
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# Returns a YAML stream containing each of the items in +objs+,
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# each having their own document.
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# YAML.dump_stream( 0, [], {} )
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def YAML.dump_stream( *objs )
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# Add a global handler for a YAML domain type.
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def YAML.add_domain_type( domain, type_tag, &transfer_proc )
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resolver.add_type( "tag:#{ domain }:#{ type_tag }", transfer_proc )
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# Add a transfer method for a builtin type
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def YAML.add_builtin_type( type_tag, &transfer_proc )
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resolver.add_type( "tag:yaml.org,2002:#{ type_tag }", transfer_proc )
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# Add a transfer method for a builtin type
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def YAML.add_ruby_type( type_tag, &transfer_proc )
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resolver.add_type( "tag:ruby.yaml.org,2002:#{ type_tag }", transfer_proc )
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# Add a private document type
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def YAML.add_private_type( type_re, &transfer_proc )
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resolver.add_type( "x-private:" + type_re, transfer_proc )
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# Detect typing of a string
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def YAML.detect_implicit( val )
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resolver.detect_implicit( val )
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# Convert a type_id to a taguri
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def YAML.tagurize( val )
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resolver.tagurize( val )
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# Apply a transfer method to a Ruby object
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def YAML.transfer( type_id, obj )
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resolver.transfer( YAML.tagurize( type_id ), obj )
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# Apply any implicit a node may qualify for
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def YAML.try_implicit( obj )
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YAML.transfer( YAML.detect_implicit( obj ), obj )
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# Method to extract colon-seperated type and class, returning
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# the type and the constant of the class
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def YAML.read_type_class( type, obj_class )
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scheme, domain, type, tclass = type.split( ':', 4 )
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tclass.split( "::" ).each { |c| obj_class = obj_class.const_get( c ) } if tclass
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return [ type, obj_class ]
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# Allocate blank object
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def YAML.object_maker( obj_class, val )
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o = obj_class.allocate
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val.each_pair { |k,v|
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o.instance_variable_set("@#{k}", v)
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raise YAML::Error, "Invalid object explicitly tagged !ruby/Object: " + val.inspect
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# Allocate an Emitter if needed
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def YAML.quick_emit( oid, opts = {}, &e )
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if opts.is_a? YAML::Emitter
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emitter.reset( opts )
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require 'yaml/rubytypes'
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# ryan:: You know how Kernel.p is a really convenient way to dump ruby
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# structures? The only downside is that it's not as legible as
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# ryan:: I know you don't want to urinate all over your users' namespaces.
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# But, on the other hand, convenience of dumping for debugging is,
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# IMO, a big YAML use case.
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# _why:: Go nuts! Have a pony parade!
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# ryan:: Either way, I certainly will have a pony parade.
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# Prints any supplied _objects_ out in YAML. Intended as
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# a variation on +Kernel::p+.
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# S = Struct.new(:name, :state)
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# s = S['dave', 'TX']
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def y( object, *objects )
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objects.unshift object
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puts( if objects.length == 1
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YAML::dump( *objects )
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YAML::dump_stream( *objects )