Python3.7 typing类型不匹配时PyCharm无提示问题求助

Hey there! I totally get how frustrating it is when you set up type hints but don't get the warnings you expect. Let's walk through the most common fixes for your issue:

1. Double-Check PyCharm's Type Inspection Settings #

First, make sure PyCharm is actually configured to flag type mismatches:

• Open File > Settings (or press Ctrl+Alt+S on Windows/Linux, Cmd+, on Mac)
• Navigate to Editor > Inspections > Python > Type checking issues
• Look for the "Incompatible types in assignment" option—ensure it's checked, and set its severity to at least "Warning" (so it shows up in your editor)
• Also, make sure other related type-checking inspections are enabled here (like "Incompatible types in return value" if you need it)

2. Verify Your Project's Python Interpreter #

Sometimes PyCharm might be using a different Python version than you think, which can break type hint support:

• Go to File > Settings > Project: [Your Project Name] > Python Interpreter
• Confirm that the selected interpreter is Python 3.7 (the version you're using for your project)
• If not, click the dropdown and select the correct 3.7 interpreter, or add it if it's missing

3. Adjust Your Type Annotation Syntax #

Your current code annotates the class-level private variable, but you're assigning to an instance variable in __init__. PyCharm might not be linking these two correctly. Try annotating the instance variable directly in __init__ instead:

from typing import List

class MyClass:
    def __init__(self):
        self.__event_ids: List[str] = 15  # You should get a type mismatch warning here now

If you still want to keep the class-level annotation, you can use ClassVar to explicitly mark it as a class variable (though that's not what you're doing here since you're assigning to an instance variable):

from typing import List, ClassVar

class MyClass:
    __event_ids: ClassVar[List[str]]  # Class-level variable
    def __init__(self):
        self.__event_ids: List[str] = 15  # Instance-level annotation for the private variable

4. Clear PyCharm's Cache #

PyCharm's cached data can sometimes cause weird behavior with inspections. Let's reset it:

• Go to File > Invalidate Caches...
• Select "Invalidate and Restart"—this will clear the cache and restart PyCharm
• Once it's back up, open your code again and check for the warning

Give these steps a try—most of the time, one of these will fix the missing warnings. If you're still having issues, double-check that you're using a recent enough version of PyCharm Professional (even though 3.7 is older, PyCharm should still support basic type checking for it).

内容的提问来源于stack exchange，提问作者jvrnt