In article <[EMAIL PROTECTED]>, greg <[EMAIL PROTECTED]> writes: |> |> > It does explain why you think of lists as homogeneous, but the |> > analogy doesn't hold water on closer inspection. There doesn't seem |> > to be ANYTHING in the specification or implementation that assumes |> > lists are homogeneous. |> |> Then what do you think is suggested by the fact |> that lists have an index() method but tuples don't?
Eh? Nothing relevant to homogeneity, to be sure. See the Library reference, 2.3.3. It starts by saying "Comparison operations are supported by all objects." and the first paragraph after the table says that == is defined to return False for different types (except numeric and string). 2.3.6 (Mutable Sequence Types) says that index returns the smallest value such that == returns True. So index finds a match among compatible types. That is an old specification of searching heterogeneous lists that I have been using for over 30 years - I can't now remember which languages include it. What's the problem? |> That's how this whole discussion got started -- |> someone wanted an explanation of why that is so. |> The explanation is that tuples and lists were |> designed for different use cases. The problem is that the homogeneity argument is irrational (which does NOT necessarily mean either wrong or undesirable), IS NOT DOCUMENTED IN THE REFERENCES, and Python is not generally irrational. My mental model of Guido is that he thinks fairly rationally. Python isn't Perl or C, after all. |> You don't *have* to use them that way, but if |> you use them differently, you're on your own |> and can't complain if they don't have all the |> features you want. Which is tantamount to saying that Python doesn't support mutable heterogeneous sequences, even though they are not locked out. That is more than just odd - it is almost unbelievable. They are a very basic data structure, after all! Regards, Nick Maclaren, University of Cambridge Computing Service, New Museums Site, Pembroke Street, Cambridge CB2 3QH, England. Email: [EMAIL PROTECTED] Tel.: +44 1223 334761 Fax: +44 1223 334679 -- http://mail.python.org/mailman/listinfo/python-list
