bpo-45243: Expose SQLite connection limits as sqlite3.Connection attributes

[erlend-aasland]

https://bugs.python.org/issue45243

[erlend-aasland]

Proposed alternative to #28463.

[erlend-aasland]

Casting the limit macros to void * and back again to int is perhaps a little bit too hackish. But it does allow for a single getter/setter.

[serhiy-storchaka]

old = con.SQLITE_LIMIT_LENGTH
con.SQLITE_LIMIT_LENGTH = new

does not look nice to me. If go this way, I would prefer

old = con.limit.length
con.limit.length = new

But do we have precedences of such getters and setters in the stdlib?

There are also disadvantages in comparison with traditional getlimit()/setlimit().

1. setlimit() sets a new limit and returns an old limit at one operation. Atomically (guarded by the GIL).
2. getlimit()/setlimit() can be used for new limits not supported by the sqlite3 module yet. Just use some numeric constant.

[erlend-aasland]

I'm not aware of similar attributes in the stdlib. I have no strong preference regarding this approach and GH-28463. I'm fine with closing this in favour of GH-28463.

[erlend-aasland]

This approach will be more tedious to maintain. I'm closing this in favour of GH-28463.