是否有类似于 C 宏的功能，它允许您以内联方式重用代码，而无需为该代码段创建单独的范围？

例如：

a=3
def foo():
a=4
foo()
print a

将打印 3，但我希望它打印 4。

我知道涉及类或全局字典等对象的解决方案，但是我正在寻找一种更原始的解决方案(例如函数装饰器)，它可以简单地让我在调用者的作用域内进行更改。

谢谢

编辑：任何需要声明我将要使用的变量或事先声明像 muttabale 对象这样的"命名空间"的解决方案都不是我正在寻找的解决方案。

我自己做了一个尝试：

def pgame():
a=3
c=5
print locals()
game(a)
print locals()

class inline_func(object):
def __init__(self, f):
self.f = f
def __call__(self, *args, **kwargs):
return self.f(*args, **kwargs)

#to be @inline_func
def game(b, a=4):
exec("inspect.stack()[3][0].f_locals.update(inspect.stack()[1] [0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))ninspect.stack()[1][0].f_locals.update(inspect.stack()[3][0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[1][0]),ctypes.c_int(0))")
try:
print "your code here"
finally:
exec("inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))")
@inline_func
def strip_game(b, a=4):
print "your code here"

但是我在如何在不破坏程序可调试性的情况下将代码注入strip_game遇到了严重的问题，因为我只想到创建一个新的代码对象或使用 exec，两者都遇到了一些严重的问题。

主要编辑：

好的，所以我有一些接近工作的解决方案，但是我遇到了一个非常奇怪的问题：

import inspect
import ctypes
import struct
import dis
import types

def cgame():
a=3
c=5
print locals()
strip_game(a)
print locals()

def pgame():
a=3
c=5
print locals()
game(a)
print locals()

class empty_deco(object):
def __init__(self, f):
self.f = f
def __call__(self, *args, **kwargs):
return self.f(*args, **kwargs)
debug_func = None
class inline_func(object):
def __init__(self, f):
self.f = f
def __call__(self, *args, **kwargs):
init_exec_string = "inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)n" + 
"ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))n" + 
"inspect.stack()[1][0].f_locals.update(inspect.stack()[3][0].f_locals)n" + 
"ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[1][0]),ctypes.c_int(0))"
fini_exec_string = "inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)n" + 
"ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))" 
co_stacksize = max(6, self.f.func_code.co_stacksize) # make sure we have enough space on the stack for everything
co_consts = self.f.func_code.co_consts +(init_exec_string, fini_exec_string)
init = "d"  + struct.pack("H", len(strip_game.f.func_code.co_consts)) #LOAD_CONST init_exec_string
init += "dx00x00x04U" # LOAD_CONST None, DUP_TOP, EXEC_STMT
init += "z" + struct.pack("H", len(self.f.func_code.co_code) + 4) #SETUP_FINALLY
fini = "Wdx00x00" # POP_BLOCK, LOAD_CONST None
fini += "d" + struct.pack("H", len(strip_game.f.func_code.co_consts) + 1) #LOAD_CONST fini_exec_string
fini += "dx00x00x04UXdx00x00S" # LOAD_CONST None, DUP_TOP, EXEC_STMT, END_FINALLY, LOAD_CONST None, RETURN
co_code = init + self.f.func_code.co_code + fini
co_lnotab = "x00x00x0b" + self.f.func_code.co_lnotab[1:] # every error in init will be attributed to @inline_func, errors in the function will be treated as expected, errors in fini will be attributed to the last line probably.
new_code = types.CodeType(
self.f.func_code.co_argcount,
self.f.func_code.co_nlocals,
co_stacksize,
self.f.func_code.co_flags & ~(1), # optimized functions are problematic for us
co_code,
co_consts,
self.f.func_code.co_names,
self.f.func_code.co_varnames,
self.f.func_code.co_filename,
self.f.func_code.co_name,
self.f.func_code.co_firstlineno,
co_lnotab,
self.f.func_code.co_freevars,
self.f.func_code.co_cellvars,)
self.inline_f =  types.FunctionType(new_code, self.f.func_globals, self.f.func_name, self.f.func_defaults, self.f.func_closure)
#dis.dis(self.inline_f)
global debug_func
debug_func = self.inline_f
return self.inline_f(*args, **kwargs)

@empty_deco
def game(b, a=4):
exec("inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))ninspect.stack()[1][0].f_locals.update(inspect.stack()[3][0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[1][0]),ctypes.c_int(0))")
try:
print "inner locals:"
print locals()
print c
return None
finally:
exec("inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))")
@inline_func
def strip_game(b, a=4):
print "inner locals:"
print locals()
print c
return None

def stupid():
exec("print 'hello'")
try:
a=1
b=2
c=3
d=4
finally:
exec("print 'goodbye'")

现在这似乎有效，但是，我得到以下内容：

>>>cgame()
{'a': 3, 'c': 5}
{'a': 4, 'c': 5, 'b': 3}
your code here
Traceback (most recent call last):
File "<pyshell#43>", line 1, in <module>
cgame()
File "C:Python27somefile.py", line 14, in cgame
strip_game(a)
File "C:Python27somefile.py", line 78, in __call__
return self.inline_f(*args, **kwargs)
File "C:Python27somefile.py", line 94, in strip_game
z = c
NameError: global name 'c' is not defined

现在当我反汇编函数时，我在game和strip_game之间得到了以下非常奇怪的编译差异：

在游戏中：

86          16 LOAD_NAME                0 (locals)
19 CALL_FUNCTION            0
22 PRINT_ITEM          
23 PRINT_NEWLINE       
87          24 **LOAD_NAME**                1 (c)
27 PRINT_ITEM          
28 PRINT_NEWLINE

在脱衣舞游戏中：

95          16 LOAD_GLOBAL              0 (locals)
19 CALL_FUNCTION            0
22 PRINT_ITEM          
23 PRINT_NEWLINE       
96          24 LOAD_GLOBAL              1 (c)
27 PRINT_ITEM          
28 PRINT_NEWLINE

为什么会出现这种差异？

在这种情况下，只需使用global关键字：

a=3
def foo():
global a
a=4
foo()
print (a)

这会修改外部作用域(如果它是全局的)。

如果外部作用域是一个函数，则使用nonlocal关键字来完成 - 这是在 Python 3.0 中引入的。

动态范围界定

然而，改变调用方函数的作用域并不是Python的前提，而是一种语言特征。

这是可以做到的。但是仅仅通过调用私有 C api(将"局部变量"值烘焙回快速局部变量)并且绝对不是一个好的做法。

通过魔术装饰器来执行它也是可能的，但是装饰器必须在内部函数中重写字节码 - 通过检索和更新调用器locals上的值来替换对"非局部"变量的每次访问，并且在函数结束时 - https://programtalk.com/python-examples/ctypes.pythonapi.PyFrame_LocalsToFast/

例

所以，也就是说，这是一个概念证明。当然，它是线程和异步不安全的 - 但如果代理类中的属性被提升为线程本地或上下文本地(PEP 555)，它应该可以工作。调整它以搜索要在调用堆栈上更改的局部变量应该很容易(因此在子子调用中所做的更改可以更改祖父母本地变量，就像在动态作用域语言中一样)

如问题中所述，没有必要将调用者上的变量声明为任何东西 - 它们必须是普通的局部变量。但是，这需要在装饰函数上声明我想在调用方作用域上更改的变量为"全局"，以便更改将通过我可以自定义的对象。如果你连这个都做不到，你确实将不得不在装饰的函数上重写字节码，或者使用用于编写调试器的钩子(在代码上设置"跟踪")。

注意更改的确切行为 locals() 最近被指定到语言中 - 在 3.8， IIRC 之前， - "locals_to_fast"似乎是一个足够稳定的 API - 但它将来可能会改变。

# Tested in Python 3.8.0
import ctypes
from functools import wraps
from sys import _getframe as getframe
from types import FunctionType

class GlobalProxy(dict):
__slots__ = ("parent", "frame", "mode")
def __init__(self, parent):
self.parent = parent
self.frame = None
self.mode = None
def __getitem__(self, name):
if self.mode == "target":
if name in self.frame.f_locals:
return self.frame.f_locals[name]
if name in self.parent:
return self.parent[name]
return getattr(self.parent["__builtins__"], name)
return super().__getitem__(name)
"""
# This is not run - Python's VM STORE_GLOBAL bypasses the custom __setitem__ (although __getitem__ above runs)
def __setitem__(self, name, value):
if name in self.frame.f_locals:
self.frame.f_locals[name] = value
bake_locals(self.frame)
self.parent[name] = value
"""
def bake_locals(self):
ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(self.frame), ctypes.c_int(1))
def save_changes(self):
self.mode = "inner"
target = self.frame.f_locals
target_names = set(target.keys())
for key in self:
if key in target_names:
target[key] = self[key]
else:
self.parent[key] = self[key]
self.bake_locals()

def caller_changer(func):
"""Makes all global variable changes on the decorated function affect _local_ variables on the callee function instead.
"""
code = func.__code__
# NB: for Python 2, these dunder-attributes for functions have other names.
# this is for Python 3
proxy = GlobalProxy(func.__globals__)
new_function = FunctionType(code, proxy, func.__name__, func.__defaults__, func.__closure__)
@wraps(func)
def wrapper(*args, **kw):
proxy.frame = getframe().f_back
proxy.mode = "target"
result = new_function(*args, **kw)
proxy.save_changes()
return result
wrapper.proxy = proxy
return wrapper

### Example and testing code:

@caller_changer
def blah():
global iwillchange
iwillchange = "new value"

def bleh():
iwillchange = "original value"
print(iwillchange)
blah()
print(iwillchange)

并且，将所有这些粘贴到IPython外壳上：

In [121]: bleh()                                                                                                                     
original value
new value

(我可以补充一点，测试感觉很奇怪，因为功能是更改局部变量不需要任何装饰器，或对变量的任何特殊声明)

好的，所以在坐了几个小时之后，我设法写了一个解决方案，在接近这个时有一些主要的陷阱，我会在下面注明

import inspect
import ctypes
import struct
import dis
import types
def dump(obj):
for attr in dir(obj):
print("obj.%s = %r" % (attr, getattr(obj, attr)))
def cgame():
a=3
c=5
print locals()
strip_game(a)
print locals()

def pgame():
a=3
c=5
print locals()
game(a)
print locals()

class empty_deco(object):
def __init__(self, f):
self.f = f
def __call__(self, *args, **kwargs):
return self.f(*args, **kwargs)

debug_func = None
class inline_func(object):
def __init__(self, f):
self.f = f
# this is the price we pay for using 2.7
# also, there is a huge glraing issue here, which is what happens if the user TRIES to access a global variable?
@staticmethod
def replace_globals_with_name_lookups(co):
res = ""
code = list(co)
n = len(code)
i = 0
while i < n:
c = code[i]
op = ord(c)
if dis.opname[op] == "STORE_GLOBAL":
code[i] = chr(dis.opmap['STORE_NAME'])
elif dis.opname[op] == "DELETE_GLOBAL":
code[i] = chr(dis.opmap['DELETE_NAME'])
elif dis.opname[op] == "LOAD_GLOBAL":
code[i] = chr(dis.opmap['LOAD_NAME'])
i = i+1
if op >= dis.HAVE_ARGUMENT:
i = i+2
return "".join(code)
def __call__(self, *args, **kwargs):
init_exec_string = "inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)n" + 
"ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))n" + 
"inspect.stack()[1][0].f_locals.update(inspect.stack()[3][0].f_locals)n" + 
"ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[1][0]),ctypes.c_int(0))"
fini_exec_string = "inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)n" + 
"ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))" 
co_stacksize = max(6, self.f.func_code.co_stacksize) # make sure we have enough space on the stack for everything
co_consts = self.f.func_code.co_consts +(init_exec_string, fini_exec_string)
init = "d"  + struct.pack("H", len(strip_game.f.func_code.co_consts)) #LOAD_CONST init_exec_string
init += "dx00x00x04U" # LOAD_CONST None, DUP_TOP, EXEC_STMT
init += "z" + struct.pack("H", len(self.f.func_code.co_code) + 4) #SETUP_FINALLY
fini = "Wdx00x00" # POP_BLOCK, LOAD_CONST None
fini += "d" + struct.pack("H", len(strip_game.f.func_code.co_consts) + 1) #LOAD_CONST fini_exec_string
fini += "dx00x00x04UXdx00x00S" # LOAD_CONST None, DUP_TOP, EXEC_STMT, END_FINALLY, LOAD_CONST None, RETURN
co_code = init + self.replace_globals_with_name_lookups(self.f.func_code.co_code) + fini
co_lnotab = "x00x00x0b" + self.f.func_code.co_lnotab[1:] # every error in init will be attributed to @inline_func, errors in the function will be treated as expected, errors in fini will be attributed to the last line probably.
new_code = types.CodeType(
self.f.func_code.co_argcount,
self.f.func_code.co_nlocals,
co_stacksize,
self.f.func_code.co_flags & ~(1), # optimized functions are problematic for us
co_code,
co_consts,
self.f.func_code.co_names,
self.f.func_code.co_varnames,
self.f.func_code.co_filename,
self.f.func_code.co_name,
self.f.func_code.co_firstlineno,
co_lnotab,
self.f.func_code.co_freevars,
self.f.func_code.co_cellvars,)
self.inline_f =  types.FunctionType(new_code, self.f.func_globals, self.f.func_name, self.f.func_defaults, self.f.func_closure)
#dis.dis(self.inline_f)
global debug_func
debug_func = self.inline_f
return self.inline_f(*args, **kwargs)

@empty_deco
def game(b, a=4):
exec("inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))ninspect.stack()[1][0].f_locals.update(inspect.stack()[3][0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[1][0]),ctypes.c_int(0))")
try:
print "inner locals:"
print locals()
print c
return None
finally:
exec("inspect.stack()[3][0].f_locals.update(inspect.stack()[1][0].f_locals)nctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(inspect.stack()[3][0]),ctypes.c_int(0))")
@inline_func
def strip_game(b, a=4):
print "inner locals:"
print locals()
print c
return None

所需的 acutal 代码在于class inline_func和一些导入(也许你可以将它们放在类内部？我真的不确定)

那么这整个事情是做什么的呢？好吧，它使strip_game和game的代码(几乎)相同，即：

它插入一个函数序幕，该序幕更新调用方的局部变量，然后将调用方的局部变量添加到被调用方。
函数周围插入 Try Final 块
将每个符号查找从全局查找更改为普通(名称)查找，经过一番思考，我意识到这实际上没有任何影响
进入 finally 块后，更新调用方本地变量。

做这样的事情有一些主要的陷阱，我将列出我遇到的几个问题：

cpythoncompiler_nameop函数根据给定函数的简单性优化命名空间查找，这意味着如果可以，它将名称查找优化为全局查找
更改字节码意味着影响程序的可调试性，我已经在co_lnotab变量中解决了这个问题
对于大型函数，此解决方案不起作用，因为某些操作码必须使用extended_args：即变量的负载和 try-finally 块(无论如何，这一点都可以通过使用extended_args来解决......

感谢@jsbueno花时间并指出我PyFrame_LocalsToFast。

附言这个解决方案适用于python 2.7.6，python在API的稳定性方面存在一些问题，因此对于较新的版本，这可能需要修复。

有没有办法声明函数应该使用调用者的作用域

主要编辑：

动态范围界定

例

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