Why tuple with one item is no tuple
apardon at forel.vub.ac.be
Fri Mar 18 11:17:35 CET 2005
Op 2005-03-16, Daniel Dittmar schreef <daniel at dittmar.net>:
> Diez B. Roggisch wrote:
>> I reread his example and have to admit I'm confused: He complains about
>> having written his _own_ vector class - and concatenation and addition had
>> to use both + ?
> I've interpreted it as:
> If Python had choosen different operators for addition and sequence
> concatenation, I could have implemented them both in my vector class. As
> it is, I have to implement one of them using a non-standard operator.
>> The examples focus too much on numbers - if we use instead
>> we would get a iterable yielding ["foo",] or - as string already supports
>> iteration - ['f', 'o', 'o']. Which one to chose?
> What I was hinting at (NOT proposing, I'd hate this) was that integers
> implement the  operator. 5  would then return 5, for all practical
> purposes, it would look like a tuple. String already implements . Yes,
> that would lead to really surprising and inconsistent behaviour.
>>>I find this 'creative use of overloading' rather awful. But what the
>>>heck, I find list comprehension rather awful.
>> Well, the number of operators built into the language is limited - and I
>> actually prefer to have the possibility to overload these if I want to.
>> Nobody forces me - I could use
>> for two vectors v1, v2 if I wanted to.
> My peeve is about having operators added to standard types. This
> increases the chances that using an object the wrong way leads to a
> bogus result, not a runtime error. A more common programming error I
> commit is passing a string where a list ist expected. And then I wonder
> why later operations work on one-character strings.
The standard answer to this seems to be to use unittesting.
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