Re: [boost] sqlpp11, 3rd iteration

Roland Bock wrote:

On 2014-08-19 16:43, Adam Wulkiewicz wrote:

...

I'm wondering, could it be possible to implement similar, compile-time interface in sqlpp, e.g. something similar to MPL? I'm asking because what the sqlpp library requires is very complicated:https://github.com/rbock/sqlpp11/blob/master/tests/Sample.h I'm aware that its purpose is to create a type reflecting required columns and to use them from the level of C++ but couldn't it be done simpler? The crucial part is the _member_t template. I need that one. The other stuff can be constructed whatever way you like. But if the name of the

column is `beta`, then I need a way to get this:

template<typename T> struct _member_t { T beta; T& operator()() { return beta; } const T& operator()() const { return beta; } };

This is the magic ingredient that makes tables, result rows and parameter sets of prepared statements to have members with a proper name.

The way it works is best to be observed in the table_t template, see https://github.com/rbock/sqlpp11/blob/master/include/sqlpp11/table.h

template struct table_t : public table_base_t, public ColumnSpec::_name_t ::template _member_t>...

Ok AFAIU a struct like _member_t should define some convenient member variable for the user and must define operator() for the library. But the rest could be automatically generated, couldn't it? Why not just pass a list of templates of classes adapted to MemberType concept (defined operator()) into the table/column/etc.? I'm thinking about something like the code below. I don't know exactly what's required so this is just an example of a technique rather than a solution ready-to-use in sqlpp. namespace sqlpp { template