Handler without engine raises error on filtered events

[vfdev-5]

🐛 Bug description

The following code does not work:

import torch
print(torch.__version__)
import ignite
print(ignite.__version__)

from ignite.engine import Engine, Events, State

def f4():
    print("f4")

    
e = Engine(lambda e, b: None)
e.state = State(iteration=0, epoch=0, max_epochs=10)

e.add_event_handler(Events.ITERATION_COMPLETED(every=2), f4)
e.fire_event(Events.ITERATION_COMPLETED)
e.fire_event(Events.ITERATION_COMPLETED)

Output

TypeErrorTraceback (most recent call last)
<ipython-input-13-832efed482dd> in <module>
     14 
     15 e.add_event_handler(Events.ITERATION_COMPLETED(every=2), f4)
---> 16 e.fire_event(Events.ITERATION_COMPLETED)
     17 e.fire_event(Events.ITERATION_COMPLETED)

/opt/conda/lib/python3.7/site-packages/ignite/engine/engine.py in fire_event(self, event_name)
    414 
    415         """
--> 416         return self._fire_event(event_name)
    417 
    418     def terminate(self) -> None:

/opt/conda/lib/python3.7/site-packages/ignite/engine/engine.py in _fire_event(self, event_name, *event_args, **event_kwargs)
    391                 kwargs.update(event_kwargs)
    392                 first, others = ((args[0],), args[1:]) if (args and args[0] == self) else ((), args)
--> 393                 func(*first, *(event_args + others), **kwargs)
    394 
    395     def fire_event(self, event_name: Any) -> None:

/opt/conda/lib/python3.7/site-packages/ignite/engine/engine.py in wrapper(engine, *args, **kwargs)
    203             event = engine.state.get_event_attrib_value(event_name)
    204             if event_filter(engine, event):
--> 205                 return handler(engine, *args, **kwargs)
    206 
    207         # setup input handler as parent to make has_event_handler work

TypeError: f4() takes 0 positional arguments but 1 was given

Environment

• PyTorch Version (e.g., 1.4): 1.6.0.dev20200411+cu101
• Ignite Version (e.g., 0.3.0): 0.4.0.dev20200412

@sdesrozis could you please take a look. Thanks !