如何获取在ruby 1.9.1上运行的to_yaml方法的格式化选项？

Question

According to the YAML documentation it's possible to pass a hash of options to the .to_yaml method.

Currently when I pass the options as suggested by the documentation it's not working, the hash is being ignored.

irb(main):001:0> require 'yaml'
=> true
irb(main):002:0> user = { "1" => { "name" => "john", "age" => 44 } }
user.to_yaml
=> "--- \n\"1\": \n  name: john\n  age: 44\n"

Now, passing some options:

irb(main):014:0> user.to_yaml( :Indent => 4, :UseHeader => true, :UseVersion => true )
=> "--- \n\"1\": \n  name: john\n  age: 44\n"
irb(main):015:0> user.to_yaml( :Separator => "\n" )
=> "--- \n\"1\": \n  name: john\n  age: 44\n"
irb(main):016:0> user.to_yaml( :separator => "\n" )
=> "--- \n\"1\": \n  name: john\n  age: 44\n"
irb(main):017:0> RUBY_VERSION
=> "1.9.1"

As you can see, passing the options don't work. Only the defaults:

YAML::DEFAULTS
=> {:Indent=>2, :UseHeader=>false, :UseVersion=>false, :Version=>"1.0", :SortKeys=>false, :AnchorFormat=>"id%03d", :ExplicitTypes=>false, :WidthType=>"absolute", :BestWidth=>80, :UseBlock=>false, :UseFold=>false, :Encoding=>:None}

Is this a known bug? or It's currently working for anyone using Ruby 1.9.1 ?

Answer 1

I have dug relatively deep into the C source for this in the not so distant past. I'm posting just to validate what's already been said in the comments.

Basically, can't do it. The Syck options get lost somewhere in the process, before ever hitting the YAML writer.

The best you can have is to_yaml_style . Sometimes.

This is the same for 1.8 and 1.9.