[Csv] This surprised me

[Skip Montanaro]

    >> Correct.  But you indicated that was no longer necessary.  I was
    >> wondering where the error checking went to.

    Andrew> I decided it wasn't necessary - if the instance has the
    Andrew> necessary bits and no more, we can use it as parameters, whether
    Andrew> it's a descendant of Dialect or not.

Yeah, but what if it has no necessary bits?  Shouldn't the user be alerted
to that fact?

    >>> import csv
    >>> class foo: pass
    ... 
    >>> rdr = csv.reader(["a,b,c\r\n"], dialect=foo)
    >>> rdr.next()
    ['a', 'b', 'c']

If nothing else, we need to define the specific defaults for the various
parameters.  In the above case, clearly my foo class isn't overriding
anything.

Skip