如何在中心工具包实现基于类名字符串的对象创建功能？

The issue with your current make_class function is that globals() in the utils module only returns the global namespace of the utils module itself—not the namespace of the main module where you defined my_class. Here are two practical fixes:

Option 1: Explicitly Pass the Caller's Global Namespace #

This is the most straightforward and transparent approach. Modify your utils function to accept the caller's globals() as an argument:

# utils.py
def make_class(class_name, caller_globals):
    try:
        cls = caller_globals[class_name]
        if not isinstance(cls, type):
            raise TypeError(f"{class_name} is not a class")
        return cls()
    except KeyError:
        raise ValueError(f"Class {class_name} not found in the provided namespace")

Then call it from your main module by passing your own globals():

# main.py
import utils

class my_class:
    def __init__(self):
        print("Instance of my_class created!")

obj = utils.make_class('my_class', globals())

Option 2: Auto-Detect the Caller's Namespace with inspect #

If you want to avoid forcing the caller to pass globals(), you can use Python's inspect module to automatically grab the caller's namespace from the call stack:

# utils.py
import inspect

def make_class(class_name):
    # Get the caller's frame (skip the current function's frame)
    caller_frame = inspect.stack()[1]
    caller_globals = caller_frame.frame.f_globals
    
    try:
        cls = caller_globals.get(class_name)
        if cls is None:
            raise ValueError(f"Class '{class_name}' not found in caller's namespace")
        if not isinstance(cls, type):
            raise TypeError(f"'{class_name}' refers to an object that's not a class")
        return cls()
    finally:
        # Clean up the frame to prevent memory leaks
        del caller_frame

Now you can use it exactly as you originally wanted:

# main.py
import utils

class my_class:
    def __init__(self):
        print("Instance of my_class created!")

obj = utils.make_class('my_class')

Notes #

• The inspect approach is convenient but has minor performance overhead, so it's best suited for small-scale use cases.
• Both methods include basic error handling to avoid crashes if the class name is invalid or not found.

内容的提问来源于stack exchange，提问作者Ray Salemi