In the context of Ruby symbols, what does "taguri" mean?

One of my colleagues and I were trying to understand why symbols are not automatically stringified when performing a regexp match on them:

>> :this =~ /./
=> false
>> :this =~ :this
=> false
>> :this =~ /:this/
=> false

One theory was that Symbol overrides the :=~ method so we checked out :this.methods. We found that Symbol does not override :=~ (1), but also noticed a very odd method:

>> :this.respond_to? :taguri=
=> true

In Japanese, たぐり (taguri) means "reeling in (thread, etc.)" (2), but I can't for the life of me figure out what that has to do with a symbol, an开发者_运维百科d I can't find Ruby source for the method in the Symbol class.

Any clues?

---

It's not "taguri" but is "Tag URI". Looking at the source code it all seems to deal with YAML and if you look in the YAML docs you see: http://ruby-doc.org/ruby-1.9/classes/YAML.html

And here's the absolute proof from tag.rb:

# Associates a taguri _tag_ with a Ruby class _cls_.  The taguri is used to give types
# to classes when loading YAML.  Taguris are of the form:
#
#   tag:authorityName,date:specific
#
# The +authorityName+ is a domain name or email address.  The +date+ is the date the type
# was issued in YYYY or YYYY-MM or YYYY-MM-DD format.  The +specific+ is a name for
# the type being added.
#
# For example, built-in YAML types have 'yaml.org' as the +authorityName+ and '2002' as the
# +date+.  The +specific+ is simply the name of the type:
#
#  tag:yaml.org,2002:int
#  tag:yaml.org,2002:float
#  tag:yaml.org,2002:timestamp
#
# The domain must be owned by you on the +date+ declared.  If you don't own any domains on the
# date you declare the type, you can simply use an e-mail address.
#
#  tag:why@ruby-lang.org,2004:notes/personal
#