[DB-SIG] dBase III and VFP tables
ethan at stoneleaf.us
Wed Jul 20 03:41:26 CEST 2011
Carl Karsten wrote:
> for those of you that are wondering about this nuttyness: VFP is a
> dBase derivative. In there early days, there was no support for Null.
> But a side effect of adding a row but not storing values to it was
> empty fields. the best example is a date. dates are stored on disk
> as a string "YYYYMMDD" and in the case of an empty date: " ".
> Same with numbers: N(6,2) would store 3.14 as " 3.14" and an empty
> number was " ". Then they added Null support, but instead of
> using this empty state, they added a flag, so now a field could be
> Null, Blank or have a value. which was a mistake, but here we are.
Thanks for the clarification, Carl.
> For D/T I am not sure you have a choice. What value would you return
> for an empty date other than Null?
As it happens, I created custom Date, Time, and DateTime objects so that
I could deal with the empty values. I probably just should have
returned None from the beginning, but did I mention that this is the
project I have learned Python with?
Now that I have them, I'm thinking of keeping and continuing to use them
for the empty case... but not sure if that's a great idea, hence my
> for Logical I would return False. Mainly because I am pretty sure
> that because in VFP an empty logical will be treated as .f. anywhere a
> logical is evaluated.
The test I tried before I left work seems to confirm that (it was just
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