How to extend a tuple of tuples?

[Thomas 'PointedEars' Lahn]

John Gordon wrote:

> […] Thomas 'PointedEars' Lahn […] writes:

It is supposed to be an attribution *line*, _not_ an attribution novel.

>> >> The obvious way does not work -
>> >>
>> >> a += (5, 6)
>>                      ^^^^^^
>> > Right, because a tuple is immutable.
> 
>> How did you get that idea?  It has been mutated in the very statement
>> that you are quoting
> 
> No.  An entirely new tuple is created, and 'a' is rebound to it.  The
> existing tuple is not mutated.

Indeed,

| $ python3
| Python 3.4.4 (default, Apr 17 2016, 16:02:33) 
| [GCC 5.3.1 20160409] on linux
| Type "help", "copyright", "credits" or "license" for more information.
| >>> t = ((1, 2), (3, 4))
| >>> t.__repr__
| <method-wrapper '__repr__' of tuple object at 0x7f4b2ddd2c08>
| >>> t += (5, 6),
| >>> t.__repr__
| <method-wrapper '__repr__' of tuple object at 0x7f4b2ddca750>

indicates that this is so.  However, this argument is purely academic, as 
that rebinding happens would neither validate Ben’s argument nor invalidate 
mine: The result obtained without the trailing comma is not so “because a 
tuple is immutable”, but because of how the expression RHS is parsed.
 
-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.