[Python-Dev] basenumber redux

[Alex Martelli]

For the last 2+ years I've been occasionally arguing for the  
introduction of a basenumber (and ideally a baseinteger, but that, to  
me, is a slightly lesser issue) analogous to basestring.  Google  
search fo [basenumber site:python.org] for several messages on the  
subject, by me and others; it will also find the recent thread about  
more general abstract baseclasses, which seems to have bogged down on  
such issues as whether sets are mappings.

Now, today, I have _again_ been bit by the lack of basenumber (by a  
bug of mine, fixed by adding decimal.Decimal to a long tuple of  
classes to be passed to an isinstance call -- I hadn't run that  
particular numeric code of mine since the time of Python 2.3,  
apparently), so I'm back to pining for it.  The previous discussion  
was short but pretty exhaustive, so I'd ask further discussants to  
refer back to it, rather than repeating it; no blocking issue appears  
to have emerged at that time, plenty of use cases were pointed out,  
etc.  Can we PLEASE have basenumber (and maybe baseinteger, so  
sequences can typecheck against that for their indices -- that's the  
key usecase of baseinteger) rather than have them "hijacked" by wider  
consideration of basesequence, basemapping, and so on...?  Pretty  
please....?  Let's be pragmatic: basenumber isn't at all complicated  
nor controversial, baseinteger hardly at all, so let's accept them  
while pondering on other potential base* classes for as long as it  
takes for the dust to settle....

I'll be happy to draft a PEP if needed (and just as happy to  
eventually provide an implementation patch if the PEP's accepted),  
but wanted to doublecheck on the general issue first!


Alex