[Numpy-discussion] Numarray 0.5

Peter Verveer verveer at embl-heidelberg.de
Wed May 7 02:17:12 CDT 2003


> > I am not sure if this is a bug, or intended behaviour, but the possibilty
> > to compare an array type object to 'Any' would be very useful for me.
>
> 'Any' grew up from the C-API,  rather than down from the Python design,
> so it's not very well thought out.  Right now,  it is a placeholder used
> to mark arrays with undefined types and to indicate "no type constraint"
> in C API calls.  In normal contexts,   you can't make an array of type
> 'Any'.  I think there are two reasonable behaviors for comparisons with
> 'Any',  both used in C.   The first behavior is literal comparison; here
> comparison to Any would generally return "not equal".  The second
> behavior is wild-card matching; here, comparison to Any would generally
> return "equal".   Which makes sense to you?  How do you want to use
> this?

I use 'Any' right now in C functions to indicate 'no type constraint'. You 
could use both literal comparison and wild-card matching behaviour for that, 
if you want to do this in Python, I think. But maybe one should not do such a 
thing in Python by comparison to 'Any' at all.

Literal comparison is what I generally expect from Python objects, so anything 
else may just be confusing (at least to me). However, the name 'Any' does 
suggest the wild-card matching behaviour. 

Is there specific reason why you exposed 'Any' in python? Maybe it would be 
better not to expose such a type object since it seems to be a 'special 
case'. I am starting to think that my use for it at the Python level is not 
appropiate. For instance, I could easily use 'None' instead, and I think I 
will do that in the future. 

You mentioned that 'Any' is really a C-API thing. Unless somebody has a good 
use for it I would now actually say that it maybe should not be exposed at 
the Python API level at all...

Cheers, Peter
 
-- 
Dr. Peter J. Verveer
Cell Biology and Cell Biophysics Programme
EMBL
Meyerhofstrasse 1
D-69117 Heidelberg
Germany
Tel. : +49 6221 387245
Fax  : +49 6221 387242
Email: Peter.Verveer at embl-heidelberg.de






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