On Sunday, 29 September 2013 at 15:42:10 UTC, simendsjo wrote:
I don't think it's that simple in this case. When I implement
lazy fetching, both methods have it's advantages and
disadvantages.
MySQL doesn't allow multiplexing on a connection. This means a
command must complete before issuing another. If reading rows
lazily and then issuing a new command, the choice is to either
disallow the new command, or invalidate the previous. The
simple way would be to just start a new command and invalidate
the previous, but is this the best way? If we choose to
disallow new commands, that means the user have to explicitly
close a lazy command. If using classes, we can safely have
several instances for a command (is this neccessary?), but then
the destructor wont't be a safe bet, and the user have to call
close.
If implemented as a struct, we have to disallow copying.
So... I really don't know what the best design would be.
I reckon go with Command being a class and invalidate previous
lazy loading on new commands being issued, you are after all
issuing a *new* command. If multiplexing is needed a new
connection can be made.
