Why is YAML throwing float ArgumentErrors on strings?

Question

I have some nested strings in a complex hash that triggers "ArgumentError" exceptions. What's the best practiced way in dealing with this?

require 'yaml'
{
    a: 'hello',
    b: [{f:'hello',g:Hash.new,i:{a:'hello'}}],
    c: {e:"+."}
}.to_yaml #=> `Float': invalid value for Float(): "+" (ArgumentError) 

Full error dump:

/Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/scalar_scanner.rb:99:in `Float': invalid value for Float(): "+" (ArgumentError)
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/scalar_scanner.rb:99:in `tokenize'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:272:in `visit_String'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:128:in `accept'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:324:in `block in visit_Hash'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:322:in `each'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:322:in `visit_Hash'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:128:in `accept'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:324:in `block in visit_Hash'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:322:in `each'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:322:in `visit_Hash'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:128:in `accept'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/visitors/yaml_tree.rb:92:in `push'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych.rb:244:in `dump'
    from /Users/XXX/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/core_ext.rb:14:in `psych_to_yaml'

Answer 1

This appears to be a bug in the bundled psych. Patching ~/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/psych/scalar_scanner.rb at line 99 from:

Float(string.gsub(/[,_]|\.$/, ''))

to:

Float(string.gsub(/[,_]|\.$/, '')) rescue ArgumentError

fixes the issue. This is essentially what's in the psych gem as well as the Ruby 1.9 bundled version.

If you'd rather not patch your Ruby, using the psych-1.3.4 gem is another option; just be sure to require 'psych' rather than 'yaml':

gem 'psych', '=1.3.4'
require 'psych'
{a: 'hello', b: [{f:'hello',g:Hash.new,i:{a:'hello'}}], c: {e:"0+."}}.to_yaml
# => "---\n:a: hello\n:b:\n- :f: hello\n  :g: {}\n  :i:\n    :a: hello\n:c:\n  :e: 0+.\n"