Where in the Ruby language is %q, %w, etc., defined?

Question

So much of the Ruby language is methods rather than syntax, so I expected to find %q, %w, etc., defined as methods in the Kernel class

Answer 1

Programming Ruby mentions them in the chapter about strings.

Related to %q{} and %Q{} is %{} which is the same as %Q{}. Also, the delimiters "{}" I show can be a matching pair of delimiters, so you could use [], (), etc. %q{} is the same as using single-quotes to delimit a string. %Q{} is the same as using double-quotes, allowing embedded strings to be interpolated:

%q{foobar} # => "foobar"
%Q{foobar} # => "foobar"

asdf = 'bar' # => "bar"
%q{foo#{asdf}} # => "foo\#{asdf}"
%Q{foo#{asdf}} # => "foobar"

Also, there is %w{} which splits a string using whitespace, into an array. For instance:

%w[a b c] # => ["a", "b", "c"]

%w{} doesn't interpolate embedded variables:

%w[a b asdf] # => ["a", "b", "asdf"]
%w[a b #{asdf}] # => ["a", "b", "\#{asdf}"]

And %r{} which defines a regular expression:

%r{^foo}.class # => Regexp

Finally there is %x{} which acts like backticks, i.e. "``", passing the string to the underlying operating system. Think of it as "exec":

%x{date} # => "Fri Nov 26 15:08:44 MST 2010\n"

A lot of Ruby's ideas for these shortcuts come from Perl, only in Perl they use q{}, qq{}, qw{}, qx{} and qr{}. The leading q stands for "quote", and they are treated and documented as "quoting" operators if I remember right. Ruby's documentation needs to be expanded, and this particular set of tools could definitely use some help.