Ruby Programming/Standard Library/Tracer

Tracer

Ruby's built-in "tracer.rb" file shows you method by method which lines are called. To use it:

 ruby -rtracer script_name.rb

for example, the following code:

class A
  def setup
    @instvar = 1
  end
  def go
    var = 2
    4.times do |@instvar|
      @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
  end
end
instance = A.new
instance.setup
instance.go

produces the following result:

C:\dev\digitalarchive_trunk>ruby -rtracer test.rb
#0:test.rb:1::-: class A
#0:test.rb:1:Class:>: class A
#0:test.rb:1:Class:<: class A
#0:test.rb:1::C: class A
#0:test.rb:2::-:     def setup
#0:test.rb:2:Module:>:     def setup
#0:test.rb:2:Module:<:     def setup
#0:test.rb:5::-:     def go
#0:test.rb:5:Module:>:     def go
#0:test.rb:5:Module:<:     def go
#0:test.rb:1::E: class A
#0:test.rb:11::-:   instance = A.new
#0:test.rb:11:Class:>:   instance = A.new
#0:test.rb:11:Object:>:   instance = A.new
#0:test.rb:11:Object:<:   instance = A.new
#0:test.rb:11:Class:<:   instance = A.new
#0:test.rb:12::-:   instance.setup
#0:test.rb:2:A:>:     def setup
#0:test.rb:3:A:-:       @instvar = 1`
#0:test.rb:4:A:<:     end`
#0:test.rb:13::-:   instance.go
#0:test.rb:5:A:>:     def go
#0:test.rb:6:A:-:       var = 2
#0:test.rb:7:A:-:       4.times do |@instvar|
#0:test.rb:7:Integer:>:       4.times do |@instvar|
#0:test.rb:8:A:-:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:Fixnum:>:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:Fixnum:<:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:A:-:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:Fixnum:>:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:Fixnum:<:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:A:-:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:Fixnum:>:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:Fixnum:<:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:A:-:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:Fixnum:>:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:8:Fixnum:<:         @instvar=@instvar*var end # <font color="#007700">#=>0,2,4,6 last assignment of @instvar is 6</font>
#0:test.rb:7:Integer:<:       4.times do |@instvar|
#0:test.rb:6:A:<:       var = 2