How is `x = 42; x = lambda: x` parsed?

Question

I was surprised that this assertion fails:

x = 42 x = lambda: x assert x() == 42 

It seems that x ends up recursively referring to itself, so that x(), x()(), etc. are all functions.

What is the rule used to parse this, and where is this documented?

By the way (not unexpectedly given the above), the original value of x has no references left after the lambda definition:

class X:   def __del__(self): print('deleting')  x = X() x = lambda: x  # 'deleting' is printed here 

Answer 1

The variable x is created by the first assignment, and rebound with the second assignment.

Since the x in the lambda isn't evaluated until the lambda is called, calling it will evaluate to the most recently assigned value.

Note that this is not dynamic scoping - if it were dynamic, the following would print "99", but it prints "<function ...":

x = 42 x = lambda: x  def test(f):   x = 99   print(f())  test(x)