From: Wilson Bilkovich <wilsonb@...>
Date: 2006-11-16T13:51:53+09:00
Subject: Catching attr_accessor with set_trace_func

Code using attr_accessor:

class User
  attr_accessor :something
  def initialize
    @something = 0
  end
end

@user = User.new

set_trace_func(lambda {|*trace| STDERR.puts trace.inspect})
@user.something

#########
prints this to STDERR:
["line", "trace_func.rb", 11, nil, #<Binding:0x2946df0>, false]
#########

Functionally equivalent code with a hand-written method, instead of
attr_accessor:

class User
  def something
    @something
  end
  def initialize
    @something = 0
  end
end

@user = User.new

set_trace_func(lambda {|*trace| STDERR.puts trace.inspect})
@user.something


#########
prints this to STDERR:
["line", "trace_func.rb", 13, nil, #<Binding:0x2946d78>, false]
["call", "trace_func.rb", 2, :something, #<Binding:0x2946c10>, User]
["line", "trace_func.rb", 3, :something, #<Binding:0x2946bc8>, User]
["return", "trace_func.rb", 4, :something, #<Binding:0x2946aa8>, User]
#########


How can I capture the fact that the 'something' accessor was called in
the first example?