bharathinmail5419 | 2020-07-19 10:31:58 UTC | #1
Can you explain more how
# Add the callback to our kwargs
self.kwargs['**progress_callback**'] = self.signals.progress
had binded to the below function
def execute_this_fn(self, progress_callback):
for n in range(0, 5):
time.sleep(1)
progress_callback.emit(n*100/4)
martin | 2020-07-19 10:39:49 UTC | #2
Hey @bharathinmail5419 welcomet to the forum!
This is making use of Python keyword unpacking. This allows you to pass keyword parameters to functions using a dictionary of key=value pairs.
When we call the execute_this_fn we call it with the following ...
execute_this_fn(**self.kwargs)
This unpacks the key=value pairs in the self.kwargs dictionary, as keywords for the function. So for example, if we had the following dictionary
my_dict = {
'something': 3,
'another': 6,
}
and then called a function as follows...
my_function(**my_dict)
this would be the equivalent of ...
my_function(something=3, another=6)
So, going back to the original example. We have a dictionary called kwargs which holds keyword arguments. We add another entry to that dictionary called 'progress_callback' which holds the function we're going to call. That could be anything, but for example say we stored the print function --
kwargs = {}
kwargs['progress_callback'] = print # Store the print function in this dictionary
If we then called our function with...
execute_this_fn(**kwargs)
That would be the equivalent of calling
execute_this_fn(progress_callback=print)
The value stored in the dictionary under progress_callback is passed as an argument with that keyword to the function.
