trace_point_usage.rb

require "binding_of_caller"

Thread.current[:current_thread_local_info] = "value set inside (main)"

class A
  def something
    t = Thread.new do
      Thread.current[:current_thread_local_info] = "value set inside A#something"

      B.new.another_thing
    end

    t.join
  end
end

class B
  def another_thing
    Thread.current[:current_thread_local_info] = "value set inside B#another_thing"
    1
  end
end

trace = TracePoint.new(:call) do |tp|
  puts "-" * 80
  t = Thread.current
  puts "current_thread_local_info: #{t[:current_thread_local_info]}"

  if tp.defined_class == A || tp.defined_class == B
    puts "self: #{tp.self}"
    puts "  line: #{tp.lineno}"
    puts "  file: #{tp.path}"
    puts "  class: #{tp.defined_class}"
    puts "  method: #{tp.method_id}"

    show_caller = lambda do |s, label=nil|
      puts "#{label || s}:       #{binding.of_caller(3).eval(s)}"
    end

    show_caller.('self', "Caller")
    show_caller.('  __FILE__')
    show_caller.('  __LINE__')
    show_caller.('  __method__')
    show_caller.('self.is_a?(Module) ? self : self.class', '  class')
  end
end


trace.enable

A.new.something



puts Thread.current[:current_thread_local_info]