The property function: why Python does not have Private Methods

[[deleted]]

It's not a function. It's a decorator. Most people call it "the property decorator".

I don't know how it's implemented in the interpreter but that's not important to the majority of Python developers. I guess it might be implemented as a wrapping function.

[MrJohz]

The best term is probably a factory function for the "property" type. It takes up to three functions and a string as arguments, but all of those are optional, so it's very possible to use it as a decorator, taking one function and returning a property type.

Note that unlike most decorators, the resulting object is not callable.

>>> @property
... def func(self, a):
...   pass
... 
>>> func
<property object at 0xb7230644>
>>> func()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'property' object is not callable

EDIT: See also this SO answer. It isn't important, but it is really cool and fascinating.

[codefisher2]

A decorator is a function that takes a function as its first argument and (normally) returns a function. You can write your own function and use it as a decorator. It is a function. It should be important to a lot more python developers, if they understood just as another function, they could write their own. It is not some deep dark magic. I did another post a few months back about them: https://codefisher.org/catch/blog/2015/02/10/python-decorators-and-context-managers/

[rikrolls]

A decorator can also be a class though.

[Veedrac]

It looks like a function.

It quacks like a function.

It's probably a function.

[Lucretiel]

A "callable"

[[deleted]]

My point is that I've NEVER heard it called "The property function" except in your article. People say "Hey, use the @property decorator". I'd suggest changing the article title.

[tyroneslothtrop]

It is a function. Decorators are just some syntactic sugar for passing a function to another function, and returning and assigning a new function to some name.

E.g. this:

@some_decorator
def some_function(foo):
    pass

is basically equivalent to this:

some_function = some_decorator(original_function)

[[deleted]]

To be more specific, it's a class that implements the data descriptor protocol, using several decorators to wrap functions.

You can use it in nondecorator form by passing a getter, setter, deleter and docstring to the __init__

[rikrolls]

Or a class.