RE: [Numpy-discussion] Extensive use of methods instead of functions

[Paul F D. <pa...@pf...>]

Every time the subject of subclassing a numeric array comes up, it as if
nobody ever thought of it before. Been there, done that. It doesn't turn =
out
to be all that useful. To see why, consider a + b where a and b are Foo
instances, and Foo inherits from numarray.

a. a + b will be a numarray, not a Foo instance, unless you write a new =
+
operator.
b. Attempting to have numarray itself apply a subclass constructor to =
the
result runs into the problem that numarray does not have any idea what =
the
constructor's signature is or what information is needed to fill out =
that
constructor.
c. Even if the subclass accepts numarray's constructor signature, it =
would
rarely produced satisfactory results just "losing" the Foo'ness details =
of a
and b.

This same argument applies to every method that returns a Foo instance, =
and
every ufunc. So you end up redoing everything anyway.

In short, worrying about subclassing is way down the list of things we =
ought
to consider.=20

> -----Original Message-----
> From: num...@li...=20
> [mailto:num...@li...] On=20
> Behalf Of Konrad Hinsen
> Sent: Friday, January 24, 2003 12:07 PM
> To: Jos=E9 Fonseca
> Cc: num...@li...
> Subject: Re: [Numpy-discussion] Extensive use of methods=20
> instead of functions
>=20
>=20
> Jos=E9 Fonseca <j_r...@ya...> writes:
>=20
> > With the ability of subclassing types in recent versions of=20
> the Python=20
> > language, more people will be interested in subclassing=20
> Numeric arrays=20
> > for specific purposes.  Still the use of functions instead=20
> of methods=20
> > takes away many of the advantages, the ability of being overloaded.
>=20
> True. On the other hand, there is also an advantage: NumPy=20
> routines can be used on standard Python data types such as=20
> number and sequence types.
>=20
> In the ideal world (which might come one day), core NumPy=20
> functionality would be part of standard Python, and then all=20
> these operations would work on other built-in types as well.
>=20
> Until then, I am not sure that changing NumPy functions to=20
> methods is a good idea. I need to call them on scalar numbers=20
> much more often than I subclass arrays.
>=20
> Konrad.
> --=20
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>=20