Is this unpythonic?

[Johannes Bauer]

On 10.05.2015 10:58, Frank Millman wrote:

> It is then a simple extra step to say -
> 
> EMPTY_L:IST = ()
> 
> and if required -
> 
> EMPTY_DICT = ()
> 
> and expand the explanation to show why a tuple is used instead.
> 
> So if there was a situation where the overhead of testing for None became a 
> problem, this solution offers the following -
> 
> 1. it solves the 'overhead' problem
> 2. it reads reasonably intuitively in the body of the program
> 3. it is safe
> 4. it should not be difficult to write a suitable self-explanatory comment

I do understand what you're trying to do, but it is my gut-feeling that
you're overengineering this and as a side-effect introducing new problems.

With the above declaration as you describe, the code becomes weird:

foo = EMPTY_LIST
foo.append(123)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'append'

and

foo = EMPTY_DICT
foo["bar"] = "moo"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment

So instead, the user of this construct would have to

foo = list(EMPTY_LIST)

or

foo = dict(EMPTY_DICT)

but, coincidentially, this is easier (and more pythonic) by doing

foo = list()
foo = dict()

to which there are the obvious (pythonic) shortcuts

foo = [ ]
foo = { }

All in all, I'd be more confused why someone would introduct
"EMPTY_LIST" in the first place and think there's some strange weird
reason behind it. Explaining the reason in the comments doesn't really
help in my opinion.

Best regards,
Johannes

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