Re: [PATCH v2 22/38] qapi/source.py: add type hint annotations

[Markus Armbruster]

John Snow <jsnow@redhat.com> writes:

> On 9/23/20 6:36 PM, Cleber Rosa wrote:
>> On Tue, Sep 22, 2020 at 05:00:45PM -0400, John Snow wrote:
>>> Annotations do not change runtime behavior.
>>> This commit *only* adds annotations.
>>>
>>> Signed-off-by: John Snow <jsnow@redhat.com>
[...]
>>> diff --git a/scripts/qapi/source.py b/scripts/qapi/source.py
>>> index e97b9a8e15..1cc6a5b82d 100644
>>> --- a/scripts/qapi/source.py
>>> +++ b/scripts/qapi/source.py
>>> @@ -11,37 +11,42 @@
>>>     import copy
>>>   import sys
>>> +from typing import List, Optional, TypeVar
>>>     
>>>   class QAPISchemaPragma:
>>> -    def __init__(self):
>>> +    def __init__(self) -> None:
>> I don't follow the reason for typing this...
>> 
>>>           # Are documentation comments required?
>>>           self.doc_required = False
>>>           # Whitelist of commands allowed to return a non-dictionary
>>> -        self.returns_whitelist = []
>>> +        self.returns_whitelist: List[str] = []
>>>           # Whitelist of entities allowed to violate case conventions
>>> -        self.name_case_whitelist = []
>>> +        self.name_case_whitelist: List[str] = []
>>>     
>>>   class QAPISourceInfo:
>>> -    def __init__(self, fname, line, parent):
>>> +    T = TypeVar('T', bound='QAPISourceInfo')
>>> +
>>> +    def __init__(self: T, fname: str, line: int, parent: Optional[T]):
>> And not this... to tune my review approach, should I assume that
>> this
>> series intends to add complete type hints or not?
>> 
>
> This is a mypy quirk you've discovered that I've simply forgotten about.
>
> When __init__ has *no* arguments, you need to annotate its return to
> explain to mypy that you have fully typed that method. It's a sentinel 
> that says "Please type check this class!"
>
> When __init__ has some arguments, you only need to type those
> arguments and not the return type. The sentinel is not needed.
>
> __init__ *never* returns anything, so I opted to omit this useless
> annotation whenever it was possible to do so.

Worth capturing in a comment and/or commit message?