我已经了解到,可以在Python中向现有对象(即,不在类定义中)添加方法。

我明白这样做并不总是好的。但你怎么能做到这一点呢?


当前回答

这实际上是对“杰森·普拉特”答案的补充

虽然Jasons的答案是有效的,但它只在想要向类中添加函数时有效。当我试图从.py源代码文件重新加载一个已经存在的方法时,它对我来说并不起作用。

我花了很长时间才找到解决方法,但技巧似乎很简单。。。1.从源代码文件导入代码2.强制重新加载3.rd使用types.FunctionType(…)将导入和绑定的方法转换为函数您还可以传递当前的全局变量,因为重新加载的方法将位于不同的命名空间中4.现在你可以按照“杰森·普拉特”的建议继续使用类型.MethodType(…)

例子:

# this class resides inside ReloadCodeDemo.py
class A:
    def bar( self ):
        print "bar1"
        
    def reloadCode(self, methodName):
        ''' use this function to reload any function of class A'''
        import types
        import ReloadCodeDemo as ReloadMod # import the code as module
        reload (ReloadMod) # force a reload of the module
        myM = getattr(ReloadMod.A,methodName) #get reloaded Method
        myTempFunc = types.FunctionType(# convert the method to a simple function
                                myM.im_func.func_code, #the methods code
                                globals(), # globals to use
                                argdefs=myM.im_func.func_defaults # default values for variables if any
                                ) 
        myNewM = types.MethodType(myTempFunc,self,self.__class__) #convert the function to a method
        setattr(self,methodName,myNewM) # add the method to the function

if __name__ == '__main__':
    a = A()
    a.bar()
    # now change your code and save the file
    a.reloadCode('bar') # reloads the file
    a.bar() # now executes the reloaded code

其他回答

from types import MethodType

def method(self):
   print 'hi!'


setattr( targetObj, method.__name__, MethodType(method, targetObj, type(method)) )

使用此选项,可以使用self指针

感谢Arturo!你的回答让我步入正轨!

根据Arturo的代码,我编写了一个小类:

from types import MethodType
import re
from string import ascii_letters


class DynamicAttr:
    def __init__(self):
        self.dict_all_files = {}

    def _copy_files(self, *args, **kwargs):
        print(f'copy {args[0]["filename"]} {args[0]["copy_command"]}')

    def _delete_files(self, *args, **kwargs):
        print(f'delete {args[0]["filename"]} {args[0]["delete_command"]}')

    def _create_properties(self):
        for key, item in self.dict_all_files.items():
            setattr(
                self,
                key,
                self.dict_all_files[key],
            )
            setattr(
                self,
                key + "_delete",
                MethodType(
                    self._delete_files,
                    {
                        "filename": key,
                        "delete_command": f'del {item}',
                    },
                ),
            )
            setattr(
                self,
                key + "_copy",
                MethodType(
                    self._copy_files,
                    {
                        "filename": key,
                        "copy_command": f'copy {item}',
                    },
                ),
            )
    def add_files_to_class(self, filelist: list):
        for _ in filelist:
            attr_key = re.sub(rf'[^{ascii_letters}]+', '_', _).strip('_')
            self.dict_all_files[attr_key] = _
        self._create_properties()
dy = DynamicAttr()
dy.add_files_to_class([r"C:\Windows\notepad.exe", r"C:\Windows\regedit.exe"])

dy.add_files_to_class([r"C:\Windows\HelpPane.exe", r"C:\Windows\win.ini"])
#output
print(dy.C_Windows_HelpPane_exe)
dy.C_Windows_notepad_exe_delete()
dy.C_Windows_HelpPane_exe_copy()
C:\Windows\HelpPane.exe
delete C_Windows_notepad_exe del C:\Windows\notepad.exe
copy C_Windows_HelpPane_exe copy C:\Windows\HelpPane.exe

此类允许您随时添加新的属性和方法。

编辑:

这里有一个更普遍的解决方案:

import inspect
import re
from copy import deepcopy
from string import ascii_letters


def copy_func(f):
    if callable(f):
        if inspect.ismethod(f) or inspect.isfunction(f):
            g = lambda *args, **kwargs: f(*args, **kwargs)
            t = list(filter(lambda prop: not ("__" in prop), dir(f)))
            i = 0
            while i < len(t):
                setattr(g, t[i], getattr(f, t[i]))
                i += 1
            return g
    dcoi = deepcopy([f])
    return dcoi[0]


class FlexiblePartial:
    def __init__(self, func, this_args_first, *args, **kwargs):

        try:
            self.f = copy_func(func)  # create a copy of the function
        except Exception:
            self.f = func
        self.this_args_first = this_args_first  # where should the other (optional) arguments be that are passed when the function is called
        try:
            self.modulename = args[0].__class__.__name__  # to make repr look good
        except Exception:
            self.modulename = "self"

        try:
            self.functionname = func.__name__  # to make repr look good
        except Exception:
            try:
                self.functionname = func.__qualname__  # to make repr look good
            except Exception:
                self.functionname = "func"

        self.args = args
        self.kwargs = kwargs

        self.name_to_print = self._create_name()  # to make repr look good

    def _create_name(self):
        stra = self.modulename + "." + self.functionname + "(self, "
        for _ in self.args[1:]:
            stra = stra + repr(_) + ", "
        for key, item in self.kwargs.items():
            stra = stra + str(key) + "=" + repr(item) + ", "
        stra = stra.rstrip().rstrip(",")
        stra += ")"
        if len(stra) > 100:
            stra = stra[:95] + "...)"
        return stra

    def __call__(self, *args, **kwargs):
        newdic = {}
        newdic.update(self.kwargs)
        newdic.update(kwargs)
        if self.this_args_first:
            return self.f(*self.args[1:], *args, **newdic)

        else:

            return self.f(*args, *self.args[1:], **newdic)

    def __str__(self):
        return self.name_to_print

    def __repr__(self):
        return self.__str__()


class AddMethodsAndProperties:
    def add_methods(self, dict_to_add):
        for key_, item in dict_to_add.items():
            key = re.sub(rf"[^{ascii_letters}]+", "_", str(key_)).rstrip("_")
            if isinstance(item, dict):
                if "function" in item:  # for adding methods
                    if not isinstance(
                        item["function"], str
                    ):  # for external functions that are not part of the class
                        setattr(
                            self,
                            key,
                            FlexiblePartial(
                                item["function"],
                                item["this_args_first"],
                                self,
                                *item["args"],
                                **item["kwargs"],
                            ),
                        )

                    else:
                        setattr(
                            self,
                            key,
                            FlexiblePartial(
                                getattr(
                                    self, item["function"]
                                ),  # for internal functions - part of the class
                                item["this_args_first"],
                                self,
                                *item["args"],
                                **item["kwargs"],
                            ),
                        )
            else:  # for adding props
                setattr(self, key, item)

让我们测试一下:

class NewClass(AddMethodsAndProperties): #inherit from AddMethodsAndProperties to add the method add_methods
    def __init__(self):
        self.bubu = 5

    def _delete_files(self, file): #some random methods 
        print(f"File will be deleted: {file}")

    def delete_files(self, file):
        self._delete_files(file)

    def _copy_files(self, file, dst):
        print(f"File will be copied: {file} Dest: {dst}")

    def copy_files(self, file, dst):
        self._copy_files(file, dst)

    def _create_files(self, file, folder):
        print(f"File will be created: {file} {folder}")

    def create_files(self, file, folder):
        self._create_files(file, folder)

    def method_with_more_kwargs(self, file, folder, one_more):
        print(file, folder, one_more)
        return self


nc = NewClass()
dict_all_files = {
    r"C:\Windows\notepad.exe_delete": {
        "function": "delete_files",
        "args": (),
        "kwargs": {"file": r"C:\Windows\notepad.exe"},
        "this_args_first": True,
    },
    r"C:\Windows\notepad.exe_argsfirst": {
        "function": "delete_files",
        "args": (),
        "kwargs": {"file": r"C:\Windows\notepad.exe"},
        "this_args_first": True,
    },
    r"C:\Windows\notepad.exe_copy": {
        "function": "copy_files",
        "args": (),
        "kwargs": {
            "file": r"C:\Windows\notepad.exe",
            "dst": r"C:\Windows\notepad555.exe",
        },
        "this_args_first": True,
    },
    r"C:\Windows\notepad.exe_create": {
        "function": "create_files",
        "args": (),
        "kwargs": {"file": r"C:\Windows\notepad.exe", "folder": "c:\\windows95"},
        "this_args_first": True,
    },
    r"C:\Windows\notepad.exe_upper": {
        "function": str.upper,
        "args": (r"C:\Windows\notepad.exe",),
        "kwargs": {},
        "this_args_first": True,
    },
    r"C:\Windows\notepad.exe_method_with_more_kwargs": {
        "function": "method_with_more_kwargs",
        "args": (),
        "kwargs": {"file": r"C:\Windows\notepad.exe", "folder": "c:\\windows95"},
        "this_args_first": True,
    },
    r"C:\Windows\notepad.exe_method_with_more_kwargs_as_args_first": {
        "function": "method_with_more_kwargs",
        "args": (r"C:\Windows\notepad.exe", "c:\\windows95"),
        "kwargs": {},
        "this_args_first": True,
    },
    r"C:\Windows\notepad.exe_method_with_more_kwargs_as_args_last": {
        "function": "method_with_more_kwargs",
        "args": (r"C:\Windows\notepad.exe", "c:\\windows95"),
        "kwargs": {},
        "this_args_first": False,
    },
    "this_is_a_list": [55, 3, 3, 1, 4, 43],
}

nc.add_methods(dict_all_files)


print(nc.C_Windows_notepad_exe_delete)
print(nc.C_Windows_notepad_exe_delete(), end="\n\n")
print(nc.C_Windows_notepad_exe_argsfirst)
print(nc.C_Windows_notepad_exe_argsfirst(), end="\n\n")
print(nc.C_Windows_notepad_exe_copy)
print(nc.C_Windows_notepad_exe_copy(), end="\n\n")
print(nc.C_Windows_notepad_exe_create)
print(nc.C_Windows_notepad_exe_create(), end="\n\n")
print(nc.C_Windows_notepad_exe_upper)
print(nc.C_Windows_notepad_exe_upper(), end="\n\n")
print(nc.C_Windows_notepad_exe_method_with_more_kwargs)
print(
    nc.C_Windows_notepad_exe_method_with_more_kwargs(
        one_more="f:\\blaaaaaaaaaaaaaaaaaaaaaaaa"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs(
        one_more="f:\\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs(
        one_more="f:\\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
    ),
    end="\n\n",
)
print(nc.C_Windows_notepad_exe_method_with_more_kwargs_as_args_first)
print(
    nc.C_Windows_notepad_exe_method_with_more_kwargs_as_args_first(
        "f:\\blaaaaaaaaaaaaaaaaaaaaaaaa"
    ),
    end="\n\n",
)
print(
    nc.C_Windows_notepad_exe_method_with_more_kwargs_as_args_first(
        "f:\\blaaaaaaaaaaaaaaaaaaaaaaaa"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs_as_args_first(
        "f:\\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs_as_args_first(
        "f:\\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
    ),
    end="\n\n",
)
print(nc.C_Windows_notepad_exe_method_with_more_kwargs_as_args_last)
print(
    nc.C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\blaaaaaaaaaaaaaaaaaaaaaaaa"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
    ),
    end="\n\n",
)
print(
    nc.C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\blaaaaaaaaaaaaaaaaaaaaaaaa"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
    ),
    end="\n\n",
)
print(nc.this_is_a_list)
checkit = (
    nc.C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\blaaaaaaaaaaaaaaaaaaaaaaaa"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ"
    )
    .C_Windows_notepad_exe_method_with_more_kwargs_as_args_last(
        "f:\\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
    )
)
print(f'nc is checkit? -> {nc is checkit}')


#output:


NewClass.delete_files(self, file='C:\\Windows\\notepad.exe')
File will be deleted: C:\Windows\notepad.exe
None


NewClass.delete_files(self, file='C:\\Windows\\notepad.exe')
File will be deleted: C:\Windows\notepad.exe
None


NewClass.copy_files(self, file='C:\\Windows\\notepad.exe', dst='C:\\Windows\\notepad555.exe')
File will be copied: C:\Windows\notepad.exe Dest: C:\Windows\notepad555.exe
None


NewClass.create_files(self, file='C:\\Windows\\notepad.exe', folder='c:\\windows95')
File will be created: C:\Windows\notepad.exe c:\windows95
None


NewClass.upper(self, 'C:\\Windows\\notepad.exe')
C:\WINDOWS\NOTEPAD.EXE


NewClass.method_with_more_kwargs(self, file='C:\\Windows\\notepad.exe', folder='c:\\windows95')
C:\Windows\notepad.exe c:\windows95 f:\blaaaaaaaaaaaaaaaaaaaaaaaa
C:\Windows\notepad.exe c:\windows95 f:\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ
C:\Windows\notepad.exe c:\windows95 f:\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
<__main__.NewClass object at 0x0000000005F199A0>


NewClass.method_with_more_kwargs(self, 'C:\\Windows\\notepad.exe', 'c:\\windows95')
C:\Windows\notepad.exe c:\windows95 f:\blaaaaaaaaaaaaaaaaaaaaaaaa
<__main__.NewClass object at 0x0000000005F199A0>


C:\Windows\notepad.exe c:\windows95 f:\blaaaaaaaaaaaaaaaaaaaaaaaa
C:\Windows\notepad.exe c:\windows95 f:\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ
C:\Windows\notepad.exe c:\windows95 f:\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
<__main__.NewClass object at 0x0000000005F199A0>


NewClass.method_with_more_kwargs(self, 'C:\\Windows\\notepad.exe', 'c:\\windows95')
f:\blaaaaaaaaaaaaaaaaaaaaaaaa C:\Windows\notepad.exe c:\windows95
f:\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ C:\Windows\notepad.exe c:\windows95
f:\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX C:\Windows\notepad.exe c:\windows95
<__main__.NewClass object at 0x0000000005F199A0>


f:\blaaaaaaaaaaaaaaaaaaaaaaaa C:\Windows\notepad.exe c:\windows95
f:\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ C:\Windows\notepad.exe c:\windows95
f:\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX C:\Windows\notepad.exe c:\windows95
<__main__.NewClass object at 0x0000000005F199A0>


[55, 3, 3, 1, 4, 43]


f:\blaaaaaaaaaaaaaaaaaaaaaaaa C:\Windows\notepad.exe c:\windows95
f:\ASJVASDFASÇDFJASÇDJFÇASWFJASÇ C:\Windows\notepad.exe c:\windows95
f:\XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX C:\Windows\notepad.exe c:\windows95


nc is checkit? -> True

至少有两种方法可以将方法附加到没有类型的实例。MethodType:

>>> class A:
...  def m(self):
...   print 'im m, invoked with: ', self

>>> a = A()
>>> a.m()
im m, invoked with:  <__main__.A instance at 0x973ec6c>
>>> a.m
<bound method A.m of <__main__.A instance at 0x973ec6c>>
>>> 
>>> def foo(firstargument):
...  print 'im foo, invoked with: ', firstargument

>>> foo
<function foo at 0x978548c>

1:

>>> a.foo = foo.__get__(a, A) # or foo.__get__(a, type(a))
>>> a.foo()
im foo, invoked with:  <__main__.A instance at 0x973ec6c>
>>> a.foo
<bound method A.foo of <__main__.A instance at 0x973ec6c>>

2:

>>> instancemethod = type(A.m)
>>> instancemethod
<type 'instancemethod'>
>>> a.foo2 = instancemethod(foo, a, type(a))
>>> a.foo2()
im foo, invoked with:  <__main__.A instance at 0x973ec6c>
>>> a.foo2
<bound method instance.foo of <__main__.A instance at 0x973ec6c>>

有用的链接:数据模型-调用描述符描述符操作指南-调用描述符

如果有什么帮助的话,我最近发布了一个名为Gorilla的Python库,以使猴子修补过程更加方便。

使用函数needle()修补名为guinepig的模块如下:

import gorilla
import guineapig
@gorilla.patch(guineapig)
def needle():
    print("awesome")

但它还处理了文档中常见问题解答中所示的更有趣的用例。

该代码在GitHub上可用。

我相信你要找的是setattr。使用此设置对象的属性。

>>> def printme(s): print repr(s)
>>> class A: pass
>>> setattr(A,'printme',printme)
>>> a = A()
>>> a.printme() # s becomes the implicit 'self' variable
< __ main __ . A instance at 0xABCDEFG>