[codesnik]

I wonder, why that kind of ambiguity or complexity even comes to your mind at all. Just because python is weird?

def foo(self, arg=expression):

could, and should work as if it was written like this (pseudocode)

def foo(self, arg?): if is_not_given(arg): arg=expression

if "expression" is a literal or a constructor, it'd be called right there and produce new object, if "expression" is a reference to an object in outer scope, it'd be still the same object.

it's a simple code transformation, very, very predictable behavior, and most languages with closures and default values for arguments do it this way. Except python.

[1718627440]

What you want is for an assignment in a function definition to be a lambda.

  def foo (self, arg=lambda : expression):

Assignment of unevaluated expressions is not a thing yet in Python and would be really surprising. If you really want that, that is what you get with a lambda.

> most languages with closures and default values for arguments do it this way.

Do these also evaluate function definitions at runtime?

[codesnik]

yes they do. check ruby for example.