From: Date: August 15 2007 12:02pm
Subject: RE: SSQLSv2 design discussion
List-Archive: http://lists.mysql.com/plusplus/6937
Message-Id: <091a01c7df23$614a09c0$0400a8c0@joel>
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Warren Young wrote:
> A side benefit of the new accessor feature is a solution to the auto
increment problem brought up recently by Graham Reitz.  Because data
members are
> hidden behind public member functions, we will know when a field has
been explicitly set ("id_is_set_ == true"), and when it retains its
default.
> If it still retains its default and it is also marked as
auto_increment, we will know to leave it out when building an INSERT or
UPDATE query.

Continuing with the Boost theme as in the "Eyeball" thread, this is
boost::optional<T> again.

Also, the ability to apply some transform as the result set goes into
the SSQLS, e.g. localising a date.  Specifically, I wouldn't want to
have to reimplement the same transform in more than one SSQLS
constructor so it would need to be templatised so that I could pass a
LocaliseDate transformer when running the select query, with the
transformer having SQLStock operator()(mysqlpp::Row& row) function.

You can achieve a similar thing with make_transform_iterator, but the
benefit would be that the transform happens once on write rather than on
each read from the container, plus of course each set of client code
wouldn't need to do the same transform in multiple places.  You can
currently also use for_each to do it, but maybe there's a place for
transform_each?

Joel