python needs leaning stuff from other language

Robert Kern robert.kern at
Sat Apr 4 22:36:07 CEST 2009

On 2009-04-04 12:07, Tim Wintle wrote:
> On Sat, 2009-04-04 at 02:03 -0500, Robert Kern wrote:
>> Let's be clear: python-ideas seems positive on the idea of adding a .clear()
>> method. *Completely removing* slice assignment has not been broached there.
> Yup, sorry - I did mean to refer to the initial suggestion, rather than
> my comments
>>> (I didn't expect such strong responses btw!)
>> You are proposing the removal of a general, orthogonal feature (and breaking
>> code in consequence!) just because of a new syntax for a single special case of
>> that feature. That is quite simply ridiculous.
> Ok, I may have come across a little strongly (was very tired) - I'm not
> _actually_ saying we should remove it, I'm just pointing out why
> adding .clear() to lists seems to be unnecessary and slightly messy. The
> suggested removal of assignments to slices is a theoretical statement.

But can you see why your wording might lead the rest of us to believe otherwise? 

>> .clear() would be non-orthogonal syntactic sugar. That's okay! Python has
>> syntactic sugar in a number of other places, too! Appropriate doses of syntactic
>> sugar and non-orthogonality are precisely what lets you implement "There should
>> be one-- and preferably only one --obvious way to do it." The really key word in
>> that sentence is "obvious", not "one".
>> FWIW, removing slice assignment would be a gross form of non-orthogonality, too.
>> __getitem__, __setitem__ and __delitem__ should all be able to accept the same
>> indices (or else raise exceptions in the case of immutability).
> hummm - I'm sure it would be confusing behaviour if it was not
> available, but I'm not sure how it would be non-orthogonal

I might be abusing the term, but to me, orthogonality doesn't just mean avoiding 
overlapping functionality. It also means not putting in special-case limitations 
for otherwise general features. It would be odd if you could use integer indices 
for __getitem__, __setitem__ and __delitem__, but slice indices would work for 
__getitem__ and not the others.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco

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