Returning self instead of None for Widget "verb" methods

[davep]

Discussed in #1817

^{Originally posted by liancheng February 16, 2023}
My app has a form-like interface, and bound one key to each widget to set focus and optionally adjust the input, e.g., toggle a switch, move the cursor to the next ListItem in a ListView, etc.

For Switches, I wrote the following method to achieve this:

def action_toggle_switch(self, selector: str) -> None:
    switch = self.query_one(selector, Switch)
    switch.focus()
    switch.toggle()

The fact that both focus() and toggle() return None prevented me from chaining the calls. If they returned self instead, the above method can be simplified to:

def action_toggle_switch(self, selector: str) -> None:
    self.query_one(selector, Switch).focus().toggle()

I'm not quite sure whether this violates certain well-established Python best practices or conventions, though.

Chatted with @willmcgugan about this and the general feeling is this would be a good thing to do (if done carefully).

[rodrigogiraoserrao]

This was implemented in #2102.

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