Ryan:
Actually, the commas used in FIRSTARGS and SECONDARGS aren't interpreted
as argument separators, but as the comma operator which is a binary
operator that evaluates both operands and returns the second one, which
explains why
MACROREQUIRINGFOURARGS( FIRSTARGS, SECONDARGS ) only sees 2 arguments
instead of 4. It's a weird little feature of C++ that very occasionally
can be useful.
The macros mentioned in this thread might be the basis for a solution to
what you're trying to do, but it's probably more trouble than it's worth:
http://www.gamedev.net/community/forums/topic.asp?topic_id=345017
Rick
Ryan W. Frenz wrote:
> On Wed, Dec 3, 2008 at 2:03 PM, Warren Young <mysqlpp@stripped> wrote:
>
>> I question how well this is going to work with MySQL to begin with, since it
>> isn't an OODB.
>>
>> You could have a separate table per subtype, but then it's impossible to
>> keep the keys synchronized among the subtype tables, so joins are
>> impossible.
>>
>
> I apologize, as I probably over-explained my problem. I already have
> my tables laid out and working in MySQL. Say I have a base with an
> int and two different derived types that inherit from it:
>
> // base.h
> class base { int id; }
>
> // derived1.h
> class derived1 : public base { std::string name; }
>
> // derived2.h
> class derived2 : public base { double d; }
>
> table derived1 looks like:
> | INT id | TEXT name |
>
> table derived2 looks like:
> | INT id | DOUBLE d |
>
> I understand the limitations of MySQL as an OODB and have designed my
> tables accordingly.
>
> I create my SSQLS for derived1 with:
> sql_create_2(derived1Struct, 1, 2, mysqlpp::sql_int, id,
> mysqlpp::sql_text, name)
>
> I create my SSQLS for derived2 with:
> sql_create_2(derived2Struct, 1, 2, mysqlpp::sql_int, id, mysqlpp::sql_double, d)
>
> This all works fine. I'm just trying to get around the fact that (in
> the above) I have 'mysqlpp::sql_int, id' hard-coded into every
> sql_create_ call.
>
> My problem is simply one of the macro-expansion I'm trying to do not
> working the way I expect. In a way more general, non mysql++ related
> example:
>
> #define FIRSTARGS a0, a1
> #define SECONDARGS a2, a3
> #define MACROREQUIRINGFOURARGS(a,b,c,d) ...
>
> MACROREQUIRINGFOURARGS(FIRSTARGS, SECONDARGS) // does not work
>
> The way I understand cpp's macro expansion, this should first expand to:
> MACROREQUIRINGFOURARGS(a0, a1, a2, a3)
>
> and as a result work fine. But I'm wrong.
>
> Thanks again,
> Ryan
>
>
