Why generate POP_TOP after an "import from?"
Adam Preble
adam.preble at gmail.com
Fri Apr 17 14:22:01 EDT 2020
Given this in Python 3.6.8:
from dis import dis
def import_from_test():
from sys import path
>>> dis(import_from_test)
2 0 LOAD_CONST 1 (0)
2 LOAD_CONST 2 (('path',))
4 IMPORT_NAME 0 (sys)
6 IMPORT_FROM 1 (path)
8 STORE_FAST 0 (path)
10 POP_TOP
12 LOAD_CONST 0 (None)
14 RETURN_VALUE
I don't understand why there's a POP_TOP there that I don't get for an import_name grammatical statement.
IMPORT_NAME needs to eat the top two entries of the stack for level and the from-list. BTW I don't know what level is for either since my science projects have always had it be zero, but that's another question.
IMPORT_NAME will the push the module on to the stack.
IMPORT_FROM will import path from the module on the stack, and push that result on the stack.
STORE_FAST will store path for use, finally "modifying the namespace."
At this point, my conceptual stack is empty. If I POP_TOP then I have nothing to pop and the world would end. Yet, it doesn't. What am I missing?
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