Handler Events as flags

[vfdev-5]

Idea is to provide the following flexibility:

@trainer.on(Events.ITERATION_STARTED(once=1) | Events.ITERATION_STARTED(every=10) | Events.COMPLETED)
def execute_some_handler(_):
    pass

such that execute_some_handler is triggered at the first iteration and at 10th, 20th, ...etc and in the end of the training.

[justusschock]

what we could most likely implement way easier is to provide something like

@trainer.on(Events.ITERATION_STARTED(once=1), Events.ITERATION_STARTED(every=10) , Events.COMPLETED)
def execute_some_handler(_):
    pass

where each argument given there is concatenated with |

[vfdev-5]

@justusschock here is a subtle detail is that the signature of

@trainer.on(<Event>, *args, **kwargs)

so, Events.ITERATION_STARTED(once=1), Events.ITERATION_STARTED(every=10) , Events.COMPLETED means <Event>=Events.ITERATION_STARTED(once=1) and others are *args...

[justusschock]

Exactly, that's why we would just have to introduce additional checks there, which will wrap them to a function, but this is way easier to implement than having them connected by the user as a boolean via |. Because currently I see no way to implement flagging behaviour without having to previously evaluate them for each possible event value.

If you're okay on separating them with ',' instead of '|', I will start implementing this.