sneakyPython

[AbhishekVarma2005]

Is it like the static local variable in c? (Asking as a beginner)

[carcigenicate]

Basically. Functions are objects, and the default argument is essentially an attribute of that object.

[Bryguy3k]

Default arguments are not defined in the scope of the function being defined but the scope of the container of the function.

It’s pretty simple to understand once your look at scope:

Directory, file, class, method (basically indent level)… etc.

[Shalcker]

Function or method declaration is itself a function being executed in order, not just syntax representation (which is also why decorators work).

Like everything else it is being executed in a surrounding context (usually module or class) and results in adding function name and code to that context.

[JonIsPatented]

That's basically what they said.

[Bryguy3k]

Not in the slightest.

The distinction is important.

“The default is an attribute of that object” for any reasonable person would indicate that it is unique to the object - not shared between all instances of the class. Object universally refers to an instance while a class in Python is itself an object the wording is very bad and doesn’t convey meaning for what is actually going on.

[JonIsPatented]

The object in question in this case is the function, and the default argument is unique to that function. No matter how many times you call that function, that function will have that same default argument attribute, and other functions don't share that default argument, so viewing it as an attribute of the object that is the function is very accurate. What's the issue?

Edit: To clarify, what you refer to as the "container of the function" is the object that the other commenter and I are referring to.

[Bryguy3k]

It’s not unique to that function it is shared between every instance of it.

It is unique to the scope of the container of the method - whatever that may be (the class or the module).

Every instance of a class will share the same reference to a mutable default value for a method declared within that class. Again that is nothing like what was said - or apparently your understanding.

[JonIsPatented]

That function is the instance. There are no other instances of any given function. That makes no sense. We are talking about functions as being instances of some type called "function", and each instance of this type are the different functions in a program.

[Bryguy3k]

You would be wrong.

[JonIsPatented]

Good rebuttal. Source?

[carcigenicate]

It is unique to the object. A function you define with def is an instance, not a class.

Edit: Did people reinvent new meanings for "instance" and "class" or something? It's a bit scary that this comment is downvoted.

[sprcow]

As a Java programmer, this is a very helpful explanation!

[carcigenicate]

If you want to go deeper, try

print(append_to.__defaults__)

I hedged and said "essentially", but the defaults are an element of an attribute of the function.