> Perhaps you should introduce IRB right at the beginning, so that people
> can play with more immediate examples.

That's a very good idea.  I'll do that.

> One suggestion - have an 'Objects' section *before* 'Variables' - start
> with defining an object (*don't* introduce the term 'object oriented
> programming', or classes - just make it seem like an object is the
> natural unit of data storage), and then segue into variables.

I see your point.  Ruby is a pure object-oriented language, so we might as
well use OO terminology.  I sort of began doing that.  For instance, I
began unsing the word 'method' right away instead of talking about
'functions' and then object orientation.

Now, a problem I have with this that I want to get the reader doing
something as soon as possible.  It is important to engage the student.

How about this?:

I can rewrite the "Variables" chapter to introduce objects right away.
I'd change the title to "Objects".  Something like this (my comments are
in [brackets]):

<<EOH
                  Objects

What is an object?

  An /object/ is the fundamental unit of data storage in Ruby.
  Objects have a /type/ (the type of data stored in them) and a /value/
  (the data itself).  Some examples include:

  Value      Type
  -----------------
     5      Fixnum
   3.14     Float
  "Hello"   String

What is a variable?

   A /variable/ is a name that Ruby can associate with a particular
   object.  For example:

   city = "Toronto"

   Here Ruby associates a String object (with value "Toronto") with
   the name (variable) /city/.

   Think of it as Ruby making two tables. One with objects and another
   with names for them.  Then think of Ruby attaching a rope between
   /city/ and the object "Toronto". Whenever Ruby encounters /city/, it
   will follow the string and arrive at this object.

Printing variables  [should I call this 'printing objects'?]

   [ Same as now ]

Object types

   We are going to look at the three most important object types:
   /Fixnum/ (integers), /Float/ (decimals), /String/ (strings).

   [
    The rest would be like what I have now, except I'd use 'Fixnum',
    'Float' and 'String' whenever possible.  I'd also mention the
    '.length' method, as you suggested.
   ]

   !Note:  Notice that the methods available depend on the object
   !       type.  Not all objects have the same methods.

   The usual convention in Ruby documentation is to write this in the form
   Type#method, so that we can say Integer#next exists, but Float#next
   doesn't.

User input and the /chomp/ method

   [ Same as before.  Use the term /String/ more. ]

Excercises

   [ Same ]

EOH

What do you think of this?

You had several other good ideas.  But I think I want to delay them for a
later chapter.

Daniel.