Python getattr()与异常处理：避免程序意外退出的正确实践

try:
    # 可能引发异常的代码
    result = 10 / 0
except ZeroDivisionError as e:
    # 处理特定异常
    print(f"发生错误: {e}")
except Exception as e:
    # 处理所有其他异常
    print(f"发生未知错误: {e}")
else:
    # 如果try块没有引发任何异常，则执行此块
    print("代码成功执行")
finally:
    # 无论是否发生异常，都会执行此块
    print("清理操作完成")

import table_builders

for b in builders_list:
    try:
        globals()[b] = getattr(table_builders, b)
        print(f'Successfully imported {b}')
    except ImportError as e: # 错误地捕获了ImportError
        print(f'\nError importing {b}. \n{e}')

# table_builders.py
class CustomersBuilder:
    def __init__(self):
        self.name = "Customers"

class FacilitiesBuilder:
    def __init__(self):
        self.name = "Facilities"

# CustomerFulfillmentPoliciesBuilder 等类可能尚未定义

import table_builders

# 示例列表，包含存在和不存在的类名
builders_list = ["CustomersBuilder", "FacilitiesBuilder", "CustomerFulfillmentPoliciesBuilder", "AnotherBuilder"]

# 使用一个字典来存储动态加载的类实例
loaded_builders = {}

for b in builders_list:
    try:
        # 尝试从 table_builders 模块获取名为 b 的属性（类）
        builder_class = getattr(table_builders, b)
        loaded_builders[b] = builder_class() # 实例化类
        print(f'Successfully loaded and instantiated {b}')
    except AttributeError as e: # 正确捕获 AttributeError
        print(f'\nError loading {b}: Attribute not found in table_builders module. Details: {e}')
    except Exception as e: # 捕获其他未知错误，以防万一
        print(f'\nAn unexpected error occurred while loading {b}: {e}')

print("\n--- Summary of Loaded Builders ---")
for name, instance in loaded_builders.items():
    print(f"Builder '{name}' loaded. Instance name: {instance.name if hasattr(instance, 'name') else 'N/A'}")

print("\n--- Builders that failed to load ---")
failed_builders = set(builders_list) - set(loaded_builders.keys())
if failed_builders:
    for fb in failed_builders:
        print(f"- {fb}")
else:
    print("None.")

import table_builders

builders_list = ["CustomersBuilder", "FacilitiesBuilder", "CustomerFulfillmentPoliciesBuilder", "AnotherBuilder"]

loaded_builders = {}

for b in builders_list:
    if hasattr(table_builders, b):
        builder_class = getattr(table_builders, b)
        loaded_builders[b] = builder_class()
        print(f'Successfully loaded and instantiated {b}')
    else:
        print(f'\nWarning: Attribute "{b}" not found in module "table_builders". Skipping.')

print("\n--- Summary of Loaded Builders (using hasattr) ---")
for name, instance in loaded_builders.items():
    print(f"Builder '{name}' loaded. Instance name: {instance.name if hasattr(instance, 'name') else 'N/A'}")

print("\n--- Builders that failed to load (using hasattr) ---")
failed_builders = set(builders_list) - set(loaded_builders.keys())
if failed_builders:
    for fb in failed_builders:
        print(f"- {fb}")
else:
    print("None.")