py/modio.c: Add SEEK_SET, SEEK_CUR and SEEK_END to io module.

[Li-Weiwei]

You can now use SEEK_SET, SEEK_CUR and SEEK_END instead of 0, 1 and 2 in
the whence parameter of the seek function.

[pfalcon]

You can now use SEEK_SET, SEEK_CUR and SEEK_END instead of 0, 1 and 2 in

No, vice-versa, you can you use 0, 1 and 2 instead of SEEK_SET, SEEK_CUR and SEEK_END. Or if you insist on using them, you can define them in your python code - all that without incurring overhead on people who don't use those constants.

[Li-Weiwei]

This makes the seek function more intuitive, just as SOCK_STREAM and SOCK_DGRAM are in the sock class.

[Li-Weiwei]

Well, that doesn't seem necessary. @pfalcon Thank you for your review.

[pfalcon]

It's true that it's more intuitive, but we also should maintain balance with code size required. As https://github.com/micropython/micropython/wiki/ContributorGuidelines suggestion, if something can be done in Python, it better be done in Python. It would be nice to drop SOCK_STREAM and SOCK_DGRAM too, but numbers behind them aren't well known and mostly consistent across systems, unlike SEEK_* constants.

Anyway, I added those to micropython/micropython-lib@7231559 (I was surprised they weren't there after 3 years - shows that people get around them pretty well).

[robert-hh]

Thanks, Paul. For me that looks like a good way dealing with Li-Weiwei's suggestion, especially since the library is meant to be the place for extensions.

[Li-Weiwei]

I have not been concerned about micropython-lib before. I used to wonder why micropython and CPython are inconsistent on some conventional parameters.
It's really best to weigh these constants into micropython-lib to balance the code size. Thanks.