create a decorator for _build_collection

[zhichen3]

An attempt to address issue #668.
Not sure if this is any better or cleaner.

[yut23]

I think something like _invalidate_collection or _modifies_rates would be better for the decorator name.

[zingale]

this looks good to me

[yut23]

Huh. Turns out making that a @staticmethod only works in 3.10+: https://stackoverflow.com/a/76237739. I think the standard practice is to move it outside the class.

[zingale]

we seemed to stall on this one. How do we want to proceed?

[zhichen3]

I completely forgot about this pr, maybe I'll try to move it outside of the class like as eric suggested.

[zhichen3]

I think this version also works, but pylint complains that I'm accessing protected member functions. Not sure what to do with this, can I just remove the underscore in the name?

[yut23]

I think renaming the decorator to modifies_rates is fine. For the other warning, you can add # pylint: disable-next=protected-access on the line before self._build_collection() to suppress it.

[zhichen3]

I think renaming the decorator to modifies_rates is fine. For the other warning, you can add # pylint: disable-next=protected-access on the line before self._build_collection() to suppress it.

thanks Eric.