Re: [Python-ideas] PEP 505: None-aware operators

July 25, 2018


      On Thu, Jul 26, 2018 at 12:00 AM Nicholas Chammas <
nicholas.chammas@gmail.com> wrote:
...
Forgive me for being slow. I'm missing what's different in semantics
between the translation above and Chris's translation below:
You are VERY close now.  You have more SPAM, so yours is better:

In [1]: class Spam:
   ...:     @property
   ...:     def eggs(self):
   ...:         print("SPAM SPAM SPAM")
   ...:         return "eggs"
   ...:
In [2]: spam = Spam()
In [3]: _tmp = spam
In [4]: if _tmp is not None:
   ...:      _tmp = _tmp.eggs
   ...:      if _tmp is not None:
   ...:          _tmp = _tmp.bacon
   ...: food = _tmp
   ...: del _tmp
   ...: food
   ...:
SPAM SPAM SPAM
---------------------------------------------------------------------
AttributeError                      Traceback (most recent call last)
<ipython-input-4-9a2f963239f8> in <module>()
      2      _tmp = _tmp.eggs
      3      if _tmp is not None:
----> 4          _tmp = _tmp.bacon
      5 food = _tmp
      6 del _tmp

AttributeError: 'str' object has no attribute 'bacon'
In [5]: if spam is not None and spam.eggs is not None:
   ...:     food = spam.eggs.bacon
   ...:
SPAM SPAM SPAM
SPAM SPAM SPAM
---------------------------------------------------------------------
AttributeError                      Traceback (most recent call last)
<ipython-input-5-a24834cdb92b> in <module>()
      1 if spam is not None and spam.eggs is not None:
----> 2     food = spam.eggs.bacon
      3

AttributeError: 'str' object has no attribute 'bacon'


-- 
Keeping medicines from the bloodstreams of the sick; food
from the bellies of the hungry; books from the hands of the
uneducated; technology from the underdeveloped; and putting
advocates of freedom in prisons.  Intellectual property is
to the 21st century what the slave trade was to the 16th.

Re: [Python-ideas] PEP 505: None-aware operators

David Mertz