std.database design suggestion

[bls]

Am 11.10.2011 13:37, schrieb Kagamin:
> bls Wrote:
>
>> abstract class DatabaseFactory {
>>
>>      public abstract Database GetDatabase();
>> }
>
> the method is usually called CreateInstance.

I think this is true for the Factory _method_ pattern. I am using the 
_Abstract_ Factory pattern.

See http://en.wikipedia.org/wiki/Abstract_factory_pattern

Though createDatabaseInstance () seems to be reasonable/ (follows common 
coding conventions)
-- slightly modified snippet--
import std.stdio;

int main(string[] args)
{
	IDatabaseFactory factory;
	
	if(args[0] == "MySQL")
		factory = new MySQLFactory();
	else
		factory = new PostreSQLFactory();

	updatePricelist(factory);
	return 0;
}

public interface IDatabase {

	
	//common database stuff
	alias open connect;	
	public void open(const string[string] params);
	
	//alias close disconnect;
	//public void close();
	
	// exec(); prepare() etc...
}

public interface IDatabaseFactory {

    public  IDatabase createDatabaseInstance();
}

final class PostgreSQL : IDatabase {

	// common
    public void open(const string[string] params) {

    }
    //PostgreSQL specific
    public void funkyPGstuff() {}
}

final class PostreSQLFactory : IDatabaseFactory {

    public IDatabase createDatabaseInstance() {

       return new PostgreSQL();

    }
}

final class MySQL : IDatabase {

	// common
    public void open(const string[string] params) {

    }
    //MySQL specific
    public void funkyMySQLstuff() {}
}

final class MySQLFactory : IDatabaseFactory {

    public IDatabase createDatabaseInstance() {

       return new MySQL();

    }
}
// Update PriceList without knowing the db backend
void updatePricelist(IDatabaseFactory factory) {
	IDatabase db = factory.createDatabaseInstance();
	db.connect([
             "host" : "localhost",
             "database" : "test",
             "user" : "bls",
             "password" : "secret"
         ]);

	//db.exec("UPDATE ...");
	
}