Queries (lxu-queries.hpp)

Classes for querying commands.

CLxCommandQuery

This class encapsulates querying the result of a command. The process is fairly simple.

• constructor -- takes the name of the command
• Arguments() -- returns an Attributes Interface as CLxUser_Attributes allowing other non-query arguments to be set
• Query() -- performs the query on the given argument index

        CLxCommandQuery          query ("item.channel");
        CLxUser_Attributes      &args = query.Arguments ();

        int arg_name = args.FindIndex ("name");
        int arg_value = args.FindIndex ("value");

        args.Set (arg_name, "camera$focalLen");
        query.Query (arg_value);

Once queried, general properties of the results can be read back.

• ValueType() -- returns the type of the queried value
• Count() -- returns the number of results
• SetIndex() -- selects a specific result index

With one of the results selected, different methods are provided to read the value in different intrinsic types.

• GetInt()
• GetFloat()
• GetString()

        n = query.Count ();
        for (i = 0; i < n; i++) {
                query.SetIndex (i);
                foclen = query.GetFloat ();
                ...
        }

CLxReadUserValue

Subclass of CLxCommandQuery, this assumes querying for user values.

• Query() -- performs the query on a named user value

        CLxReadUserValue user;

        if (user.Query ("my_user_value"))
                my_int = user.GetInt ();