En Fri, 31 Jul 2009 17:26:58 -0300, Emmanuel Surleau
<emmanuel.surl...@gmail.com> escribió:
On Friday 31 July 2009 21:55:11 Terry Reedy wrote:
The word tuple comes from relational databases as a generalization of
single, double, triple, quadruple, quintuple, sextuple, sestuple,
octuple, etc. A tuple is a data record with a fixed number of fields
with individual meaning. There is nothing about homogeneity of data type
in that definition. A triple of floats is legitimately a tuple when each
is a coordinate (the individual meanings). In other contexts, the same
triple might properly be a list (such as of heights of people
arbitrarily ordered).
My understanding is that, in this context, it's not so much data types
which
are heterogeneous, but the semantic meaning of the data. For instance, a
tuple
containing (first_name, last_name, address) would be a "legitimate"
tuple, but
not a tuple containing (address, address, address), which, if we follow
Guido's philosophy, ought to be represented as a list.
Note that years ago the distinction was much stronger: tuples had NO
methods at all. All you could do with a tuple was: len(t), t[i], t1+t2,
t*n, e in t, for e in t
Being so "crippled", thinking of tuples just as immutable lists probably
wasn't so natural.
--
Gabriel Genellina
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