f---ing typechecking

[skip at pobox.com]

    Sergey> posix.stat_result is CLASS, not regular tuple.

    >> I believe it morphed from being a tuple though.  I wasn't suggesting
    >> that

    Sergey> It it morphed, the tuple nature of it is just history now.

No, it is still full of tuple-fu:

    >>> import os
    >>> s = os.stat("/etc/hosts")
    >>> s
    (33188, 92111L, 26738688L, 1, 0, 1, 355L, 1171570459, 1164401316,
    1171087243)
    >>> type(s)
    <type 'posix.stat_result'>
    >>> s.st_mtime
    1164401316
    >>> s[0:3]
    (33188, 92111L, 26738688L)
    >>> s[4:] + s[0:3]
    (0, 1, 355L, 1171570459, 1164401316, 1171087243, 33188, 92111L, 26738688L)
    >>> type(s[4:] + s[0:3])
    <type 'tuple'>

    >> The notion of tuples as records in Python is not new:
    >> http://mail.python.org/pipermail/python-list/1999-December/thread.html
    >> Search for "super tuples".

    Sergey> Did it go beyond just talking?

Raymond Hettinger just proposed adding a pure Python implementation to
Python 2.6.  The version he's been using for about a year is here:

    http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/500261

    Sergey> We can think about tuples anything, but are they something other
    Sergey> than freezed lists?  We can index them, slice, iterate,
    Sergey> map/redice/filter, can cast (fuckin C!)  to lists and back -
    Sergey> what the difference??  "Tuples is similar to records" - I think
    Sergey> this is just topological artefact, generated when python was
    Sergey> compared with some other languague :)

The fact that tuples and lists share so many implementation details makes
people think of tuples as immutable lists.  That view has its uses (allowing
you to pretend that you can use lists as dictionary keys or take advantage
of the compile-time allocation of tuples of constants, for example), but I
don't think that makes the view of tuples as records a "topological
artifact".  I'm not sure where you believe Python was compared to some other
language.  My original comment was that tuples could be thought of more like
C structs or Pascal records.  That was an analogy, not a language
comparison.

    Sergey> classes have sintactically and functionally overcame
    Sergey> records/structs - why to drag to the same role tuples, that have
    Sergey> not initially any feature of record?

They have a number of record-like features.  They are relatively compact
(unlike class instances), once instantiated they can't be extended (unlike
lists or class instances in the common case).  They just don't yet have
named attributes.

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