new component element and hot-reloading about pyedifice

[jamesdbrock]

To see hot reloading succeed and fail, check out branch hotreload1 which restores the old example tutorial program.

Hot reloading works:

python -m edifice examples/tutorial.py MyApp

Hot reloading doesn't work:

python -m edifice examples/tutorial_old.py MyApp

[considerate]

My immediate thought is that this might be related to the children prop

[jamesdbrock]

When hot reloading the new tutorial.py on this line

pyedifice/edifice/engine.py

Line 444 in 14ba471

kwargs = {k: old_comp.props[k] for k, v in parameters[1:]

We have

old_comp.props = PropsDict({'children': []})

and

parameters = [
0: ('self', <Parameter "self">)
1: ('args', <Parameter "*args: P.args">)
2: ('kwargs', <Parameter "**kwargs...P.kwargs">)

So we get Exception has occurred: KeyError 'args'.

When hot reloading the tutorial_old.py on that line

parameters = [('self', <Parameter "self">)]

[jamesdbrock]

This is the hard part. We must somehow construct a new Element, using the required constructor arguments, which are the kwargs props. It doesn't have to be the right props, because we can just assign the right props on the next line after the Element is constructed. But constructing it is tricky.

pyedifice/edifice/engine.py

Line 455 in 14ba471

parts[3] = new_comp_class(**kwargs)