[Python-ideas] Fwd: Define a method or function attribute outside of a class with the dot operator

Joao S. O. Bueno jsbueno at python.org.br
Fri Feb 10 07:13:46 EST 2017

I am definetelly -1 to this idea.

But since you are discussing this seriously, one nice thing is to
recall how Javascript does that:
`function <name> () ` is an expression that returns the created
function, and thus can be assigned to anything on
the left side.

Of course, that would throw us back to a way of thinking of inline
definition of multiline functions -
which is another requested and unresolved thing in Python.

(But we might require the `def` statement to still be aligned, at
least style-wise, and require
people to write

Foo.foo =\
def (self, ...): ...


That said, this possibility in Javascript is the source of severe
inconsistencies in how functions are declared across different
libraries and projects, and IMHO, makes reading (and writting) a real pain.

(And, as stated above, a two line decorator could make for the patching -
it does not need to have such an ugly name as "monkey_patch" - it
could be just "assign" instead)


On 10 February 2017 at 09:51, Steven D'Aprano <steve at pearwood.info> wrote:
> On Fri, Feb 10, 2017 at 10:05:30PM +1100, Chris Angelico wrote:
>> * What would the __name__ be? In "def ham.spam():", is the name "spam"
>> or "ham.spam"?
> "spam" of course, just like it is now:
> py> class Ham:
> ...     def spam(self):
> ...             ...
> ...
> py>
> py> Ham.spam.__name__
> 'spam'
> You might be thinking of __qualname__:
> py> Ham.spam.__qualname__
> 'Ham.spam'
>> Or say you have "def x[0]():" - is the name "x[0]" or
>> something else?
> I wouldn't allow that. I feel that "any assignment target at all" is an
> over-generalisation, a case of YAGNI.
> It is relatively easy to change our mind and add additional cases in the
> future, but very difficult to remove them if they turn out to be a
> mistake.
> My intuition tells me that we should allow :
>     def name dot name (args):
> possibly even more than one dot:
>     def name dot name dot name ... (args):
> but no additional cases:
>     # syntax error
>     def spam[0]function(): ...
> --
> Steve
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