Commit 113f9fa9 by David Hotham Committed by GitHub

fix: late binding closure in ApplicationPlugin

B023:  Functions defined inside a loop must not use variables redefined in the loop, because late-binding closures are a classic gotcha.

Here's some sample code approximating the poetry code:
```python
#!/usr/bin/env python3


def one() -> int:
    return 1


def two() -> int:
    return 2


def three() -> int:
    return 3


factories = [one, two, three]

registered = []
for factory in factories:
    registered.append(lambda: factory())

for registered_factory in registered:
    print(f"result is {registered_factory()}")
```
output is
```
result is 3
result is 3
result is 3
```
which is exactly the gotcha that flake8-bugbear's B023 was trying to warn about.

I've applied one of the workarounds that various parts of the internet recommend, and you can verify for yourself if you're so inclined that doing the same in the toy script gives the expected output.
parent 0a5e4b5f
...@@ -24,6 +24,4 @@ class ApplicationPlugin(BasePlugin): ...@@ -24,6 +24,4 @@ class ApplicationPlugin(BasePlugin):
def activate(self, application: Application) -> None: def activate(self, application: Application) -> None:
for command in self.commands: for command in self.commands:
assert command.name is not None assert command.name is not None
application.command_loader.register_factory( application.command_loader.register_factory(command.name, command)
command.name, lambda: command() # noqa: B023
)
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