inspect vs. to_s

gistfile1.rb

# Example 1
# "Empty" instance
#################################################

class Foo; end
foo = Foo.new

# will be true in 1.8.7 and 1.9.2 as no instance variables are defined
foo.inspect == foo.to_s 

# Example 2
# Instance with instance variable
#################################################

class Foo
  def initialize; @foo = "foo"; end
end
foo = Foo.new

# will be false in 1.8.7 and 1.9.2
foo.inspect == foo.to_s
# foo.inspect returns:  "#<Foo:0x00000100a5e618 @foo=\"foo\">"
# foo.to_s returns:     "#<Foo:0x00000100a5e618>"

# Example 3
# With defined to_s
#################################################

class Foo
  def to_s; "Hello from Foo"; end
end

# will be false in 1.8.7 but true in 1.9.2
foo.inspect == foo.to_s 
# A call of +to_s+ will be the same obviously, but +inspect+ differs.
# 1.8.7: "#<Foo:0x103437db8 @foo=\"foo\">"
# 1.9.2: "Hello from Foo"

# And all that because of http://redmine.ruby-lang.org/issues/1786