Out of interest, tested snippet in PyCharm, cf native-mypy. It flags the
original:
GLOBALS.foos: Optional[Foos]=Foos()
but not the fall-back:
GLOBALS.foos=Foos()
Must admit, the first query coming to mind was: why is the typing taking
place at initialisation-time, rather than within the (class) definition?
At definition time "foos" has already been typed as None by implication!
Solution (below) will not work if the mention of Foos in GLOBALS is a
forward-reference. Either move GLOBALS to suit, or surround "Foos" with
quotes.
Also, these days (Python version allowing) importing "List" is
unnecessary. Instead could use "list".
On 30/10/2022 10.23, Sam Ezeh wrote:
Do you want the following?
```
from typing import List, Optional
class GLOBALS:
foos: Optional[Foos] = None
class Foo:
def __init__(self):
pass
class Foos:
Foos: List[Foo] = []
def __init__(self):
pass
GLOBALS.foos = Foos()
```
Kind regards,
Sam Ezeh
On Sat, 29 Oct 2022 at 22:13, Paulo da Silva <
p_d_a_s_i_l_v_a...@nonetnoaddress.pt> wrote:
Hi!
Consider this simple script ...
___________________
from typing import List, Optional
class GLOBALS:
foos=None
class Foo:
def __init__(self):
pass
class Foos:
Foos: List[Foo]=[]
# SOME GLOBALS ARE USED HERE in a real script
def __init__(self):
pass
GLOBALS.foos: Optional[Foos]=Foos()
___________________
Running mypy on it:
pt9.py:18: error: Type cannot be declared in assignment to non-self
attribute
pt9.py:18: error: Incompatible types in assignment (expression has type
"Foos", variable has type "None")
Line 18 is last line and pt9.py is the scrip.
Replacing last line by
GLOBALS.foos=Foos()
and running mypy still gives the second error.
pt9.py:18: error: Incompatible types in assignment (expression has type
"Foos", variable has type "None")
What is the common practice in these cases?
Thank you.
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Regards,
=dn
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