feat: Use factory mode to init the operator instance in Python binding

[Zheaoli]

          This could be better

class Operator:
    @classmethod
    def from_config(scheme: str, **kwargs)-> Operator: ...

    @classmethod
    def from_async_operator(operator: AsyncOperator) -> Operator: ...

class AsyncOperator:
    @classmethod
    def from_config(scheme: str, **kwargs)-> AsyncOperator: ...

    @classmethod
    def from_operator(operator: Operator) -> AsyncOperator: ...

We use the factory mode instead of __init__ completely

Originally posted by @Zheaoli in #3514 (comment)

[Xuanwo]

I want to preserve the naming of from_config to make space for us to introduce RFC-3197: Config for bindings.

[Xuanwo]

By the way, is the API style like from_xxx widely used in python?

[Zheaoli]

By the way, is the API style like from_xxx widely used in python?

Nope, a normal way

https://github.com/mitmproxy/mitmproxy/blob/746537e0511e0316a144e05e7ba8cc6f6e44768b/mitmproxy/coretypes/serializable.py#L30-L37

https://github.com/mitmproxy/mitmproxy/blob/746537e0511e0316a144e05e7ba8cc6f6e44768b/mitmproxy/certs.py#L378-L406

[Xuanwo]

Nope, a normal way

I don't understand this statement.

Nope, a normal way means it does be widely used?

[Zheaoli]

Nope, a normal way

I don't understand this statement.

Nope, a normal way means it does be widely used?

Sorry for confusing

I mean, this is a normal style from_xxx in Python. Many project use this conversion in factory mode

https://github.com/search?q=%22def+from_%22+repo%3Atensorflow%2Ftensorflow&type=code&ref=advsearch

[Xuanwo]

I mean, this is a normal style from_xxx in Python.

Got it, thanks for sharing.

[Zheaoli]

I mean, this is a normal style from_xxx in Python.

Got it, thanks for sharing.

BTW, from_xxx is good pattern which is suggested in PEP8 "Explicit is better than implicit"

[Xuanwo]

Seems cool, would you like to propose an RFC for python binding about this change? We can place them inside bindings/python/docs/rfcs.

---

This is the first RFC for python binding!

[Zheaoli]

Seems cool, would you like to propose an RFC for python binding about this change? We can place them inside bindings/python/docs/rfcs.

This is the first RFC for python binding!

Of course!

[Zheaoli]

@Xuanwo BTW, would you mind me adding a new label "RFC needed` to represent an issue which okay but needs a RFC before submitting the code

[Xuanwo]

@Xuanwo BTW, would you mind me adding a new label "RFC needed` to represent an issue which okay but needs a RFC before submitting the code

I don't think we need this.

[asukaminato0721]

I check the code, #3514 added the instance method, not class method, and #3197 is merged, so any other things need to be solved?