Template

You had seem generic when we talk about function.

type DbORM<DbT: type> (
    DB: DbT
)

impl DbORM {
    +connect(port_conf: str) {
        self.DB.connect(port_conf)
    } 
    +execute(sql: str) {
        self.DB.execute(sql)
    }
    +close() {
        self.DB.close()
    }
}

If template at type, don't repeat it again.

You don't need to do that.

Specialize

impl DbORM<MySQL> {
    // ...
}

What!? You just say don't do that! I heard.

Because write like this won't work like you think. It will specialize the DbORM this part's code.

When DbT != MySQL, this part code would not be impl.

impl DbORM<MySQL> {
  +connect() { ... }
  +execute(sql: str) { ... }
}

DbORM<SQLServer> do not have 'xxx'

So you need to realize, MySQL existed, or specialize won't be implemented.