Re: My little comments to CPP code

[sergey@total-knowledge.com]

I mentioned in my first message in this thread that

> sergey@total-knowledge.com wrote:
> One thing that is not working is session_info related queries(b/c DB pool
> functionality isn't implemented yet), but I tested the logic manually and
> it seems good to me.

The reason for submitting a code was to demonstrate other parts of the code.
Thanks for suggestions though.


> Gentlemen,
>
> I'm not sure how far we are from the working prototype, but the following
> code would never work correctly:
>
> +bool User::setSessionInfo(string login, string password, int server,
> string
> sessionid)
> +{
> +
> +  CODBCDatabase db("DSN=PostgreSQL;UID=sergey;PWD=;DATABASE=uu");
> +  try {
> +    CQuery qryInsert(&db,"select login('"+login+"', '"+password+"',
> "+lexical_cast<string>(server)+")");
> +    qryInsert.exec();
> +  }
> +  catch (exception& e) {
> +    cout<<"\nError: " <<e.what();
> +    return false;
> +  }
> +  return true;
> +
> +}
>
> Here is how it works now:
>
> 1) The database object is created.
> 2) Query is executed. Since the connection wasn't open yet, query makes
> database object to open a connection. Execution of the query creates
> temporary table session_info and fills it with user information.
> 3) Query and database objects go out the scope with the return. Connection
> is closed in database object destructor. Temporary table that is local to
> connection is destroyed by Postgres server.
>
> As result, we have no effect on the database.
>
> The workaround may be the following (for instance): We make CDatabase* a
> member of User class. It's created in User ctor and destroyed in user
> dtor.
> All the time in between it must stay open.
>
> Also, I'd do the code within try a little bit different, like this:
>
> try {
>    CQuery qryInsert(&db,"select login(:login,:password,:server)");
>    qryInsert.param("login") = login;
>    qryInsert.param("password") = password;
>    qryInsert.param("server") = server; // this should be an integer
> parameter, use course_server table as a source
>    qryInsert.exec();
> }
>
> Now, in this particular approach it just looks longer than original
> version.
> However, as we get to slightly more complex queries, it makes the query
> syntax much more clear.
> Also, in most of the cases, SPTK uses binary data with no need for
> conversion to string. In many cases, it's faster, too.
>
> --
> Alexey Parshin,
> http://www.sptk.net
>