method

set_trace_func

v1_8_7_330 - Show latest stable - 0 notes - Class: Kernel

set_trace_func(p1) public

Establishes proc as the handler for tracing, or disables tracing if the parameter is nil. proc takes up to six parameters: an event name, a filename, a line number, an object id, a binding, and the name of a class. proc is invoked whenever an event occurs. Events are: c-call (call a C-language routine), c-return (return from a C-language routine), call (call a Ruby method), class (start a class or module definition), end (finish a class or module definition), line (execute code on a new line), raise (raise an exception), and return (return from a Ruby method). Tracing is disabled within the context of proc.

  class Test
  def test
    a = 1
    b = 2
  end
  end

  set_trace_func proc { |event, file, line, id, binding, classname|
     printf "%8s %s:%-2d %10s %8s\n", event, file, line, id, classname
  }
  t = Test.new
  t.test

    line prog.rb:11               false
  c-call prog.rb:11        new    Class
  c-call prog.rb:11 initialize   Object
c-return prog.rb:11 initialize   Object
c-return prog.rb:11        new    Class
    line prog.rb:12               false
    call prog.rb:2        test     Test
    line prog.rb:3        test     Test
    line prog.rb:4        test     Test
  return prog.rb:4        test     Test

Show source

/*
 *  call-seq:
 *     set_trace_func(proc)    => proc
 *     set_trace_func(nil)     => nil
 *  
 *  Establishes _proc_ as the handler for tracing, or disables
 *  tracing if the parameter is +nil+. _proc_ takes up
 *  to six parameters: an event name, a filename, a line number, an
 *  object id, a binding, and the name of a class. _proc_ is
 *  invoked whenever an event occurs. Events are: <code>c-call</code>
 *  (call a C-language routine), <code>c-return</code> (return from a
 *  C-language routine), <code>call</code> (call a Ruby method),
 *  <code>class</code> (start a class or module definition),
 *  <code>end</code> (finish a class or module definition),
 *  <code>line</code> (execute code on a new line), <code>raise</code>
 *  (raise an exception), and <code>return</code> (return from a Ruby
 *  method). Tracing is disabled within the context of _proc_.
 *
 *      class Test
 *      def test
 *        a = 1
 *        b = 2
 *      end
 *      end
 *
 *      set_trace_func proc { |event, file, line, id, binding, classname|
 *         printf "%8s %s:%-2d %10s %8s\n", event, file, line, id, classname
 *      }
 *      t = Test.new
 *      t.test
 *
 *        line prog.rb:11               false
 *      c-call prog.rb:11        new    Class
 *      c-call prog.rb:11 initialize   Object
 *    c-return prog.rb:11 initialize   Object
 *    c-return prog.rb:11        new    Class
 *        line prog.rb:12               false
 *        call prog.rb:2        test     Test
 *        line prog.rb:3        test     Test
 *        line prog.rb:4        test     Test
 *      return prog.rb:4        test     Test
 */


static VALUE
set_trace_func(obj, trace)
    VALUE obj, trace;
{
    rb_event_hook_t *hook;

    rb_secure(4);
    if (NIL_P(trace)) {
        trace_func = 0;
        rb_remove_event_hook(call_trace_func);
        return Qnil;
    }
    if (!rb_obj_is_proc(trace)) {
        rb_raise(rb_eTypeError, "trace_func needs to be Proc");
    }
    trace_func = trace;
    for (hook = event_hooks; hook; hook = hook->next) {
        if (hook->func == call_trace_func)
            return trace;
    }
    rb_add_event_hook(call_trace_func, RUBY_EVENT_ALL);
    return trace;
}

set_trace_func

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