如何在__init__之前向类添加属性？

Question

Question

I have a Python module that creates instances of many other modules at runtime. The other modules are specified via an external configuration file, which also houses all arguments/values for each module's __init__ .

I would like to add the same attribute to all new instances, but I don't want to add a new arg to __init__ on all of my classes. How can I go about this?

My Thoughts

One possible solution: on the fly, I can add a new arg to __init__ by somehow manipulating the __init__ attribute on the module. Then I can pass it the attribute I want to add on all instances.

I am pretty sure this violates the Zen of Python. That being said, I am curious how one could do this?

Answer 1

You could iterate over the **kwargs __init__ parameter and use __setattr__ to automatically set any new passed parameter. Example:

class Foo:
    def __init__(self, **kwargs):
        for key in kwargs:
            self.__setattr__(key, kwargs[key])

You would only have to blindly add these two lines plus the **kwargs argument to your classes, then:

f = Foo(name="bar")
print(f.name)

Output:

bar