TYP: tighten IO Protocols

[twoertwein]

and to ensure that changes of pandas-dev/pandas#48144 also work.

[Dr-Irv]

It's not clear to me why we have to declare the methods of these various Buffer types for the public stubs, as users wouldn't instantiate those classes.

Is the goal to make it so that what we have in public pandas for these types in _typing.py is the same as in _typing.pyi in pandas-stubs ?

[twoertwein]

It's not clear to me why we have to declare the methods of these various Buffer types for the public stubs

Not having some of those mehods/properties can lead to errors such as pandas-dev/pandas#45488 and more obvious errors (not having a read method for buffers used for reading - surprise). pandas._typing has comments for which feature each method is needed. We cannot use typing.IO as it requires way too many methods/properties (see python/typeshed#4212) so I tried to add the minimal needed methods/properties in pandas-dev/pandas#43951 (with an update in pandas-dev/pandas#48144).

as users wouldn't instantiate those classes.

These are protocols, they don't need to be instantiated (like typing.IO). The current tests of pandas-stubs show that all the current IO tests still work fine :)

Is the goal to make it so that what we have in public pandas for these types in _typing.py is the same as in _typing.pyi in pandas-stubs ?

That's a secondary goal.

[twoertwein]

All the buffers are used as input arguments (not as return values), so we can remove not needed optional arguments to be compatible with a wider class of IO functions that might or might not implement optional keywords.