On Thu, 28 Feb 2008 11:13:27 -0500, D'Arcy J.M. Cain wrote:
>> > Automatic conversions, okay... but converting a result when all
>> > inputs are of one time, NO...
>>
>> What? How does that make any sense?
>>
>> By that logic, we should see this:
>>
>> >>> len("a string")
>> '8'
>> >>> len([2, 4, 6])
>> [3]
>> >>> len({'key': 'value'})
>> {1: None}
>
> I think that you have to show your work here. How does the above
> statement about operators imply that the len method should return the
> type of its argument?
Consider the argument list to the function call len("a string").
>>> args = ["a string"] # all the arguments
>>> all(type(arg) == str for arg in args)
True
So therefore all the arguments to len() in this case are of a single
type, namely str, and by Dennis' assertion, "converting a result when all
inputs are of one [type], NO...", should return the same type as all the
arguments. Which for the avoidance of all doubt is str.
Similarly for the case len([2, 4, 6]), except this time all the arguments
(all one of them) are lists, and therefore len() should return a list.
Naturally it's a crazy argument. Which is my point. Operators are merely
a different syntax for functions of two arguments, and any restriction
that functions must return the same type as all its arguments is just
crazy.
> > And rightly rejected by many other programming languages, including
> > modern Python, not to mention calculators, real mathematics and
> > common sense.
>
> Lost me again. I was not aware that calculators, real mathematics
> and common sense were programming languages.
I didn't say they were. Please parse my sentence again.
--
Steven
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