"Rance Hall" <ran...@gmail.com> wrote
I'd like to be able to just ask the question again, and re-validate
the new input or offer a "press q to quit" option
Thats what loops are for...
The old GOTO syntax that everybody hates was ideal for this type of
thing, if validation fails, just goto the question again and re-ask
it.
Nope, it wasn't ideal and thats why it was removed from most
languages.
Structured Loops are better.
So how do you do this?
You either write a loop that cycles until you get valid input or you
could create a heirarchy of Field classes(*) that know how to request
input
and validate it. If the data is invalid they request input again -
which
takes us back to loops...
(*) Or even a single Validator class that takes a validation function
as
an input parameter....
One possible loop would look something like:
a = b = c = None
dataOK = False
while not dataOK:
if not a:
a = raw_input('Enter a: ')
if not validA(a):
a = None
continue
if not b:
b = raw_input('Enter b: ')
if not validB(b):
b = None
continue
if not c:
c = raw_input('Enter a: ')
if not validC(c):
c = None
continue
And since the input blocks are repeated you could even
convert them to a function if you really cared or had a lot
of fields.
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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