From: stephen.hill@... (Steve Hill)
Date: 2001-08-07T00:00:39+09:00
Subject: [ruby-talk:19219] symbols for global constants

Hi
I'm getting a bit confused about global constants and class names
(using ruby 1.6.2)

Suppose I define a class Foo. Then (according to the pickaxe book
p253) there is a global constant Foo which references an object of
class Foo. This is what enables me to pass Foo as an argument to a
function (as given in the example)

def factory(klass, *args)
   klass.new(*args)
end

factory(String,"Hello") -> "Hello"

OK, so this is all well and good. But what happens now if I have a
string containing the name of the class I want to create from the
factory (the context of my question is parsing a meta file).

So, after adding the above example, I tried the following on irb

irb > factory(String,"hello")
"hello"

irb > factory ("String","hello")
NameError: undefined method `new' for String:Symbol
....

OK, so I didn't expect that to work (although that would have been
pushing the "principle of least surprise" too far if it had done :-)

I was more surprised that the following did not work

irb > factory ("String".intern, "hello")
NameError: undefined method `new' for :String:Symbol
....

Does anybody have any idea how to achieve this functionality?

Best regards

Steve