Re: [TCLCORE] null handling and TIP #185

[Twylite <tw...@cr...>]

>
> From: rna020 <tom...@fr...>
>   
> This can be handled by the simple suggestions being proposed by the "no 
> NULL in tcl" side of the discussion. What isn't clear, at least to me, 
> is weather these ideas scale to more complicated cases in SQL and other 
> situations like holes in lists.
>   
That really depends on the people specifying the APIs for those subsystems.
If the "nextrow" in TDBC returned a list of tuples where each tuple was 
"column-name type value" then we wouldn't be having this discussion 
about NULLs because they could be indicated in the type field of the tuple.
On the other hand we _would_ be having discussions about how to easily 
and efficiently retrieve individual values and entire rows from this 
list-of-tuples, which is why I haven't proposed it seriously ;)

Any API that deals with NULLs on the C side is going to have to 
translate the concept intelligently in a domain-specific manner to Tcl.  
The file/chan, Tk, and other APIs manage to do this gracefully.  SQL is 
somewhat special in that there are times when you want to know _in Tcl 
code_ whether the DBMS / SQL query returned a NULL or not.

Regards,
Twylite