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Outputs a source level execution trace of a Ruby program.
It does this by registering an event handler with Kernel#set_trace_func for processing incoming events. It also provides methods for filtering unwanted trace output (see ::add_filter, ::on, and ::off).
Consider the following ruby script
class A def square(a) return a*a end end a = A.new a.square(5)
Running the above script using ruby -r tracer example.rb
will
output the following trace to STDOUT (Note you can also explicitly
require 'tracer'
)
#0:<internal:lib/rubygems/custom_require>:38:Kernel:<: - #0:example.rb:3::-: class A #0:example.rb:3::C: class A #0:example.rb:4::-: def square(a) #0:example.rb:7::E: end #0:example.rb:9::-: a = A.new #0:example.rb:10::-: a.square(5) #0:example.rb:4:A:>: def square(a) #0:example.rb:5:A:-: return a*a #0:example.rb:6:A:<: end | | | | | | | | | ---------------------+ event | | | ------------------------+ class | | --------------------------+ line | ------------------------------------+ filename ---------------------------------------+ thread
Symbol table used for displaying incoming events:
call a C-language routine
return from a C-language routine
call a Ruby method
C
start a class or module definition
E
finish a class or module definition
-
execute code on a new line
raise an exception
return from a Ruby method
by Keiju ISHITSUKA(keiju@ishitsuka.com)
Symbol table used for displaying trace information
Reference to singleton instance of Tracer
Used to filter unwanted trace output
Example which only outputs lines of code executed within the Kernel class:
Tracer.add_filter do |event, file, line, id, binding, klass, *rest| "Kernel" == klass.to_s end
# File tracer.rb, line 271 def Tracer.add_filter(p = proc) Single.add_filter(p) end
Disable tracing
# File tracer.rb, line 244 def Tracer.off Single.off end
Register an event handler p
which is called everytime a line
in file_name
is executed.
Example:
Tracer.set_get_line_procs("example.rb", lambda { |line| puts "line number executed is #{line}" })
# File tracer.rb, line 258 def Tracer.set_get_line_procs(file_name, p = proc) Single.set_get_line_procs(file_name, p) end