Method: TracePoint.new

Defined in:

vm_trace.c

.new(*args) ⇒ Object

TracePoint.new(*events) { |obj| block } -> obj

Returns a new TracePoint object, not enabled by default.

Next, in order to activate the trace, you must use TracePoint.enable

trace = TracePoint.new(:call) do |tp|

p [tp.lineno, tp.defined_class, tp.method_id, tp.event]

end #=> #<TracePoint:disabled>

trace.enable #=> false

puts “Hello, TracePoint!” # … # [48, IRB::Notifier::AbstractNotifier, :printf, :call] # …

When you want to deactivate the trace, you must use TracePoint.disable

trace.disable

See TracePoint@Events for possible events and more information.

A block must be given, otherwise a ThreadError is raised.

If the trace method isn’t included in the given events filter, a RuntimeError is raised.

TracePoint.trace(:line) do |tp|

p tp.raised_exception

end #=> RuntimeError: ‘raised_exception’ not supported by this event

If the trace method is called outside block, a RuntimeError is raised.

TracePoint.trace(:line) do |tp|
  $tp = tp
end
$tp.line #=> access from outside (RuntimeError)

Access from other threads is also forbidden.

# File 'vm_trace.c', line 1234

static VALUE
tracepoint_new_s(int argc, VALUE *argv, VALUE self)
{
    rb_event_flag_t events = 0;
    int i;

    if (argc > 0) {
	for (i=0; i<argc; i++) {
	    events |= symbol2event_flag(argv[i]);
	}
    }
    else {
	events = RUBY_EVENT_TRACEPOINT_ALL;
    }

    if (!rb_block_given_p()) {
	rb_raise(rb_eThreadError, "must be called with a block");
    }

    return tracepoint_new(self, 0, events, 0, 0, rb_block_proc());
}