[Python-Dev] trunc()

[M.-A. Lemburg]

On 2008-01-27 08:14, Raymond Hettinger wrote:
>> . You may disagree, but that doesn't make it nuts.
> 
> Too many thoughts compressed into one adjective ;-)
> 
> Deprecating int(float)-->int may not be nuts, but it is disruptive.
> 
> Having both trunc() and int() in Py2.6 may not be nuts, but it is duplicative and confusing.
> 
> The original impetus for facilitating a new Real type being able to trunc() into a new Integral type may not be nuts, but the use 
> case seems far fetched (we're never had a feature request for it -- the notion was born entirely out of numeric tower 
> considerations).
> 
> The idea that programmers are confused by int(3.7)-->3 may not be nuts, but it doesn't match any experience I've had with any 
> programmer, ever.
> 
> The idea that trunc() is beneficial may not be nuts, but it is certainly questionable.
> 
> In short, the idea may not be nuts, but I think it is legitimate to suggest that it is unnecessary and that it will do more harm 
> than good.

All this reminds me a lot of discussions we've had when we
needed a new way to spell out string.join().

In the end, we ended up adding a method to strings (thanks to
Tim Peters, IIRC) instead of adding a builtin join().

Since all of the suggested builtins are only meant to work on
floats, why not simply add methods for them to the float object ?!

E.g.

x = 3.141
print x.trunc(), x.floor(), x.ceil()

etc.

This approach also makes it possible to write types or classes
that expose the same API without having to resort to new special
methods (we have too many of those already).

Please consider that type constructors have a different scope
than helper functions. Helper functions should only be made builtins
if they are really really useful and often needed. If they don't
meet this criteria, they are better off in a separate module.
I don't see any of the suggested helper functions meeting this
criteria and we already have math.floor() and math.ceil().

-- 
Marc-Andre Lemburg
eGenix.com

Professional Python Services directly from the Source  (#1, Jan 28 2008)
>>> Python/Zope Consulting and Support ...        http://www.egenix.com/
>>> mxODBC.Zope.Database.Adapter ...             http://zope.egenix.com/
>>> mxODBC, mxDateTime, mxTextTools ...        http://python.egenix.com/
________________________________________________________________________

:::: Try mxODBC.Zope.DA for Windows,Linux,Solaris,MacOSX for free ! ::::


   eGenix.com Software, Skills and Services GmbH  Pastor-Loeh-Str.48
    D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg
           Registered at Amtsgericht Duesseldorf: HRB 46611