some problems for an introductory python test

[Hope Rouselle]

Terry Reedy <tjreedy at udel.edu> writes:

> On 8/10/2021 5:27 PM, Hope Rouselle wrote:
>> Terry Reedy <tjreedy at udel.edu> writes:
>> 
>>> On 8/10/2021 9:15 AM, Hope Rouselle wrote:
>>>>>>> 2.__add__(3)
>>>> SyntaxError: invalid syntax
>>>> But then I tried:
>>>>
>>>>>>> (2).__add__(3)
>>>> 5
>>>
>>> Add a space is easier.
>>>>>> 2 .__add__(3)
>>> 5
>>>>>>
>> Hah.  That's brilliant!  So cool.
>
> Python is a little looser about whitespace than one might expect from
> reading 'normal' code when the result is unambiguous in that it cannot 
> really mean anything other than what it does.  Two other examples:
>
>>>> if3: print('yes!')
> yes!

That's cool to know too, but I would have expected that.  Programming
languages tend to ignore whitespace as much as possible.  (But someone
followed-up with more details...  I'll get there.)  But the next one...

>>>> [0]  [0]
> 0

Oh!  This almost fooled me.  It's just a list containing the integer
zero followed by the index-operator (or however the brackets are called
in this case.)

At first I thought maybe there was an implicit operator between lists
just like it happens with strings.

>>> "a" "," "b"
'a,b'

But which operator would it be?  It wasn't concatenation, of course.  So
I looked at what type() thought of it.  Then I tried changing numbers:

>>> [1] [1]
Traceback (most recent call last):
  File "<pyshell#13>", line 1, in <module>
    [1] [1]
IndexError: list index out of range

And that's when it hit me. :-)  Thanks!