Import module doesn't updated

[cheny0y0]

BPO	41770
Nosy	@terryjreedy, @stevendaprano, @cheny0y0

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-09-18.23:09:22.379>
created_at = <Date 2020-09-12.03:00:14.826>
labels = ['interpreter-core', 'invalid', 'type-bug', '3.8']
title = "Import  module doesn't updated"
updated_at = <Date 2020-09-18.23:09:22.378>
user = 'https://github.com/cheny0y0'

bugs.python.org fields:

activity = <Date 2020-09-18.23:09:22.378>
actor = 'terry.reedy'
assignee = 'none'
closed = True
closed_date = <Date 2020-09-18.23:09:22.379>
closer = 'terry.reedy'
components = ['Interpreter Core']
creation = <Date 2020-09-12.03:00:14.826>
creator = 'prasechen'
dependencies = []
files = []
hgrepos = []
issue_num = 41770
keywords = []
message_count = 5.0
messages = ['376766', '376767', '376770', '376818', '377142']
nosy_count = 3.0
nosy_names = ['terry.reedy', 'steven.daprano', 'prasechen']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue41770'
versions = ['Python 3.8']

[cheny0y0]

# I create a module:
# \sys.path\xxx.py
a = 9
# And:
>>> import xxx
>>> xxx.a
9
# I delete this imported module and modified this module:
del xxx
# \sys.path\xxx.py
a = 9
b = 8
# And re-import:
>>> import xxx
>>> xxx.b
# But:
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: type object 'xxx' has no attribute 'b'

[pmp-p]

Hi, you just need to call del sys.modules['xxx'] and have a look at https://docs.python.org/3.7/library/importlib.html#importlib.invalidate_caches

before importing again

[stevendaprano]

This is not a bug, it is working as designed. Importing takes the module from the cache. You can either delete the module from the cache:

del sys.modules['modulename']
import modulename  # reloads from the module file

or possibly simpler, use reload:

    importlib.reload(modulename)