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Avoid calling __init__ for classmethod/staticmethod #450
Description
Suppose we want a CLI that is similar to git in the sense that we must first call init before interacting with the repo. For this, we aim for the following (simplified/partially implemented) class, which is intentionally similar to GitPythons Repo class (see here):
from pathlib import Path
import fire
class SomethingLikeGit:
dirname = ".something_like_git"
@classmethod
def init(cls, path=None):
path = Path(path or Path.cwd())
path = path / cls.dirname
print("Initializing at", path)
path.mkdir()
...
print("Done.")
def __init__(self, path=None):
path = Path(path or Path.cwd())
for parent in (path, *path.parents):
self.path = parent / self.dirname
if self.path.exists():
break
else:
raise FileNotFoundError(path)
...
if __name__ == "__main__":
fire.Fire(SomethingLikeGit)When we run the command python something_like_git.py init, it first tries to instantiate the class via __init__, which fails (FileNotFoundError) since it must first create the directory via init.
I think it makes generally more sense if Fire would call classmethods/staticmethods directly on the class without trying to instantiate it. This is usually also how class/static methods are used in a programmatic way (e.g. for git.Repo).
Note that the fix for #113 does not resolve this issue. This is because the path argument for __init__ is (intentionally) optional, so Fire thinks it can call __init__ first. If path wasn't optional, it would behave as wanted: init would be called without first calling __init__.
Anyway, thanks for your great work!
Activity
RAGHAV2405AR commentedon Mar 16, 2026
Hi, I was able to reproduce the behavior described in this issue.
Reproduction
Using the example code
Running:
produces:
This happens because Fire attempts to instantiate the class before calling
init(). Since__init__(path=None)has an optional argument, Fire assumes it can safely construct the class first.Workaround
A simple workaround is to expose CLI commands instead of passing the class directly to
fire.Fire().Example:
With this approach, running:
correctly produces:
This prevents Fire from calling
__init__beforeinit().Let me know if you'd like me to open a PR adding this workaround as an example in the documentation.