Support psych YAML parser

[wjordan]

What would be required for this backend to support projects that currently depend on the psych YAML parser? I have a project that could definitely benefit from this faster i18n backend, but it seems like syck is a requirement.

[jenseng]

It would take a bit of refactoring to the C extension to leverage Psych (or more accurately libyaml). It is on my todo list, but I don't have an ETA for it yet.

That said, Psych and Syck can live along side each other. For example, I've got a Rails 4.1 app (Ruby 2) that uses the built-in Psych for any YAMLy stuff, yet I18nema is able to use Syck:

irb(main):014:0> I18n.backend
=> #<I18nema::Backend:0x007f9a847ed198 @translations=#<I18nema::Backend:0x007f9a898c9ee0>, @normalized_key_cache=#<I18nema::Backend:0x007f9a898c9e68>, @initialized=true>
irb(main):015:0> I18n.backend.direct_lookup("en", "hello")
=> "Hello world"
irb(main):016:0> YAML.parse('foo: bar')
=> #<Psych::Nodes::Document:0x007f9a8382aeb8 @children=[#<Psych::Nodes::Mapping:0x007f9a8382ae68 @children=[#<Psych::Nodes::Scalar:0x007f9a8382adf0 @value="foo", @anchor=nil, @tag=nil, @plain=true, @quoted=false, @style=1>, #<Psych::Nodes::Scalar:0x007f9a8382ada0 @value="bar", @anchor=nil, @tag=nil, @plain=true, @quoted=false, @style=1>], @anchor=nil, @tag=nil, @implicit=true, @style=1>], @version=[], @tag_directives=[], @implicit=true, @implicit_end=true>

But yeah, it's something I plan to support so you don't have to have both installed.

[wjordan]

A related issue using I18nema alongside Psych is that the to_yaml methods end up using the Syck engine by default, even if the YAML::ENGINE.yamler property is overridden. Here's a workaround we had to add to an initializer in order to have to_yaml method find the Psych engine as expected:

  YAML::ENGINE.yamler = 'psych'
  # We need to remove the :to_yaml methods Syck injects into certain classes (Psych only uses Object::to_yaml)
  # Class list is from syck-1.0.1/lib/syck/rubytypes.rb
  %w(Class Hash Struct Array Exception String Symbol Range Regexp
  Time Date Integer Float Rational Complex TrueClass FalseClass NilClass).each do |x|
    x.constantize.send(:remove_method, :to_yaml) if x.constantize.instance_methods(false).include?(:to_yaml)
  end

[technicalpickles]

The workaround doesn't seem to work anymore since Ruby 2.2: https://github.com/ruby/syck/issues/9

[ccutrer]

unfortunately, this project is no longer supported. we haven't used it internally for ~5 years, in favor of just using the regular i18n gem. it never made the jump to Psych, and hasn't been a high enough priority to maintain. feel free to fork it and continue using it yourself.