在python中，我必须实例化某个类，知道它在字符串中的名称，但这个类“生活”在一个动态导入的模块中。示例如下:
loader类脚本:
import sys
class loader:
def __init__(self, module_name, class_name): # both args are strings
try:
__import__(module_name)
modul = sys.modules[module_name]
instance = modul.class_name() # obviously this doesn't works, here is my main problem!
except ImportError:
# manage import error
some-dynamically-loaded-module脚本:
class myName:
# etc...
我使用这种安排使加载器类使用任何动态加载模块，遵循动态加载模块中的某些预定义行为…
当前回答
如果你想从字符串中导入一个类和方法，你应该这样做:
dynamic_import
│ my_class.py
│
└───subfolder
│ │ my_subfolder_module.py
│ │
my_subfolder_module.py
class MySubfolderClass():
def test_method(self):
print ("Hello World")
main.py
import importlib
module = importlib.import_module('subfolder.my_subfolder_module')
class_ = getattr(module, "MySubfolderClass")
method_instance = getattr(class_(),"test_method")
method_instance()
#it will output the result of the test method, which is "Hello World"
其他回答
使用getattr从字符串中的名称中获取属性。换句话说，获取实例为
instance = getattr(modul, class_name)()
可以简单地使用pydoc。定位功能。
from pydoc import locate
my_class = locate("module.submodule.myclass")
instance = my_class()
如果你想从foo中得到这句话。Bar import foo2来动态加载，你应该这样做
foo = __import__("foo")
bar = getattr(foo,"bar")
foo2 = getattr(bar,"foo2")
instance = foo2()
复制粘贴代码片段:
import importlib
def str_to_class(module_name, class_name):
"""Return a class instance from a string reference"""
try:
module_ = importlib.import_module(module_name)
try:
class_ = getattr(module_, class_name)()
except AttributeError:
logging.error('Class does not exist')
except ImportError:
logging.error('Module does not exist')
return class_ or None
如果你想从字符串中导入一个类和方法，你应该这样做:
dynamic_import
│ my_class.py
│
└───subfolder
│ │ my_subfolder_module.py
│ │
my_subfolder_module.py
class MySubfolderClass():
def test_method(self):
print ("Hello World")
main.py
import importlib
module = importlib.import_module('subfolder.my_subfolder_module')
class_ = getattr(module, "MySubfolderClass")
method_instance = getattr(class_(),"test_method")
method_instance()
#it will output the result of the test method, which is "Hello World"
