Working with Tags

I noticed today that an undefined tag appears to be simply thrown away.

    o = YAML.load('--- !foo "something"')  #=> "something"
    o.class  #=> String

I actually expected it to raise an error, and was somewhat pleased that it did not. But without the tag it's not much use in any case. What would be useful is a YAML wrapper around the object that delegates to it, but also provides a #tag method (and anything else that YAML might need), something like:

    o = YAML.load('--- !foo "something"')  #=> <!foo "something">
    o.tag #=> "!foo"
    o.to_obj #=> "something"

This would make working with YAML documents that use tags much easier, b/c it would mean handlers would not have to be defined upfront and with necessary pre-knowledge. Rather they could be handled on the fly and even dynamically if desired.

I've been thinking about this for some time as I routinely find myself avoiding any use of YAML tags simply b/c of the cumbersome nature of handling them.

Start with the YAML.load example in the issue and trace how an undefined !foo tag is currently handled. Define the wrapper behavior around the tagged value, including tag access and conversion to the underlying object. Done means tagged YAML values retain their tag and can still expose the wrapped value without requiring a handler in advance.