Comparisons and sorting of a numeric class....

Andrew Robinson andrew3 at r3dsolutions.com
Wed Jan 7 03:53:23 CET 2015


On 01/06/2015 06:34 PM, Terry Reedy wrote:
> On 1/6/2015 9:01 PM, Andrew Robinson wrote:
>
> [snip]
>
> There are very few (about 4) builtin classes that cannot be 
> subclassed.  bool is one of those few, float is not.  Go ahead and 
> subclass it.
>
> >>> class F(float): pass
>
> >>> F
> <class '__main__.F'>
> >>> F(2.3) + F(3.3)
> 5.6
>
>
Thanks terry! That's a relief.  Ive just managed to find a few classes 
that won't subtype by trial and error in the last two months and was 
getting pessimistic.  ( eg: doing web pages I wanted to customize the 
error output traceback stack from a python script based on where the 
exception occurred..... UUUUGH!  I worked around the no sub-typing 
issue, but it took a lot of guessing to trick python into accepting a 
fake class to the print traceback functions the webserver used... )




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