On Mar 4, 1:14 am, Robert Bradshaw <[email protected]>
wrote:
> I think it's fair to test for strings first, trying to parse, before
> testing if it's an iterator. This is consistant with many other
> objects that try to "parse" their string representations.
>
> sage: ZZ['x']([1,2,3])
> 3*x^2 + 2*x + 1
> sage: ZZ['x']("123")
> 123
> sage: ZZ['x']("x^2 + 5")
> x^2 + 5
Indeed. It's not quit consistent with duck typing, but well ...
I guess matrix(S) would do:
if isinstance(S,basestring):
<do our best to parse S as a string rep of a matrix>
else:
try:
V=iter(S)
#figure out how to interpret the elements of V
#(are they rows or elements?)
#should we accept strings at this point?
#the CSV example above indicates that with a known base ring,
#allowing elements of V to be iterables of strings representing
elements
#seems a good idea.
except TypeError:
#do whatever we do with non-iterable matrix initializers
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