[DB-SIG] Use of context managers with DB API 2

[Vernon Cole]

Christoph, I think you may be Dutch -- your design proposal feels right to
me.
(+1) from Vernon

On Fri, Nov 2, 2012 at 3:53 AM, Christoph Zwerschke <cito at online.de> wrote:

>
> What I find a bit ugly about this approach is that now the context
> managers of connections and cursors behave differently, and that code
> written using these context managers is not self-explanatory. If
> connections and cursors would just have closing context managers, and
> connections had an extra "transaction" member that is a context manager for
> handling the transaction, the code would be more readable and explicit
> which is better than implicit:
>
>     with dbapi2.connect(...) as con:
>         with con.transaction:
>             with con.cursor() as cur:
>                 cur.execute("insert into debit(amount) values (-100)")
>                 cur.execute("insert into credit(amount) values (100)")
>         with con.transaction:
>             with con.cursor() as cur:
>                 cur.execute("insert into debit(amount) values (-200)")
>                 cur.execute("insert into credit(amount) values (200)")
>
> Or, when using the shortcut methods:
>
>     with dbapi2.connect(...) as con:
>         with con.transaction:
>             con.execute("insert into debit(amount) values (-100)")
>             con.execute("insert into credit(amount) values (100)")
>         with con.transaction:
>             con.execute("insert into debit(amount) values (-200)")
>             con.execute("insert into credit(amount) values (200)")
>
>
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