From: Derek Ney <derek@...>
Date: 2001-10-02T16:49:06+09:00
Subject: [ruby-talk:21930] Question mark in instance variable

I recently tried using a question mark as the suffix for an instance
variable and discovered problems. I assume that it is just not
a good idea, but was curious what was supposed to be happening.
With this code snippet:

    class QTest
      attr_accessor :shown?
    end
    
    q = QTest.new
    print "initially q.shown? = ", q.shown?, "\n"
    q.shown? = true
    print "q.shown? = ", q.shown?, "\n"

I get this:
    /tmp/test.rb:7: parse error
    q.shown? = true

I have tried all different combos of spaces/nonspaces around the = sign
to no avail. However, clearly the internals do support this, it seems
to be just a parser problem, because this code works:

    class QTest
      attr_accessor :shown?
    end
    
    q = QTest.new
    print "initially q.shown? = ", q.shown?, "\n"
    q.__send__("shown?=".intern, true)
    print "q.shown? = ", q.shown?, "\n"

Produces:
    initially q.shown? = nil
    q.shown? = true

So, is this just a flaw in the parser? Or is it intended? It would be nice
if you could use question marks, as it is a very nice feature for methods
and has similar uses for instance variables (accessors).  This was all with
ruby 1.7.1 (2001-09-20).
-Thanks, Derek Ney