Bug #9358: TracePoint's raise event should throw 'not supported by this event (RuntimeError)' on calling return_value

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.1.0

[andhapp (Anuj Dutta)]

=begin
Hello,

In TracePoint class, if a particular introspection method is not supported then 'not supported by this event (RuntimeError)' is thrown.

=== Line event doesn't support raised_exception

 TracePoint.trace(:line) do |tp|
   p tp.raised_exception
 end

 #=> RuntimeError: 'raised_exception' not supported by this event

However, that doesn't seem to happen for 'raise' event. The call to return_value stops the trace altogether. Here's the code to reproduce it:

=== Code

class Car
def self.start
begin
raise StandardError.new, 'Error!'
rescue
end
end
end

TracePoint.trace(:raise) do |tp|
p tp.raised_exception
p [tp.return_value, tp.raised_exception]
end

Car.start

=== Expected Output
#=> #<StandardError: Error!>
#=> `return_value': not supported by this event (RuntimeError)

=== Actual Output
#=> #<StandardError: Error!>

Is this expected behaviour?

Thanks

=end

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed
• Backport deleted (1.9.3: UNKNOWN, 2.0.0: UNKNOWN, 2.1: UNKNOWN)

This is expected behavior. As the documentation states:

raised_exception: Value from exception raised on the :raise event
return_value: Return value from :return, c_return, and b_return event

You cannot call methods not supported by the type. You can use the event method to check the type of the particular event.