Python에서 특정 클래스의 모든 인스턴스를 효과적으로 확인하려면 어떻게 해야 합니까?

<code class="python">import gc

for obj in gc.get_objects():
    if isinstance(obj, some_class):
        # Perform desired operations on 'obj'</code>

<code class="python">from collections import defaultdict
import weakref

class KeepRefs(object):
    # Dictionary to store weak references to class instances
    __refs__ = defaultdict(list)

    def __init__(self):
        # Add weak reference to self within class-level dictionary
        self.__refs__[self.__class__].append(weakref.ref(self))

    @classmethod
    def get_instances(cls):
        # Iterate through weak references and return valid instances
        for inst_ref in cls.__refs__[cls]:
            inst = inst_ref()
            if inst is not None:
                yield inst

class X(KeepRefs):
    def __init__(self, name):
        # Invoke base class constructor with required parameters
        super(X, self).__init__()
        self.name = name

# Create instances of class X
x = X("x")
y = X("y")

# Retrieve and print instance names
for r in X.get_instances():
    print(r.name)

# Remove one of the instances
del y

# Re-retrieve and print remaining instance names
for r in X.get_instances():
    print(r.name)</code>