[英]Is there a way to declare that a function should use the scope of the caller?
是否有类似于 C 宏的功能，可让您以内联方式重用代码，而无需为那段代码创建单独的 scope？
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，但是我正在寻找一个更原始的解决方案（例如 function 装饰器），它只会让我在调用者的 scope 内部进行更改。
非常感谢您
编辑：任何需要声明我将使用哪些变量或事先声明像 mutabale 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。
我自己尝试过：
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"
但是我遇到了一个严重的问题，即如何在不破坏程序可调试性的情况下将代码注入strip_game ，因为我只想创建一个新代码 object 或使用 exec，两者都遇到了一些严重的问题。
好的，所以我有一些接近工作解决方案的东西，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 += "d\x00\x00\x04U" # LOAD_CONST None, DUP_TOP, EXEC_STMT
init += "z" + struct.pack("H", len(self.f.func_code.co_code) + 4) #SETUP_FINALLY
fini = "Wd\x00\x00" # 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 += "d\x00\x00\x04UXd\x00\x00S" # 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 = "\x00\x00\x0b" + 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'")
现在这似乎可行，但是，我得到以下信息：
>>>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:\Python27\somefile.py", line 14, in cgame
strip_game(a)
File "C:\Python27\somefile.py", line 78, in __call__
return self.inline_f(*args, **kwargs)
File "C:\Python27\somefile.py", line 94, in strip_game
z = c
NameError: global name 'c' is not defined
现在，当我反汇编这些函数时，我得到以下game和strip_game之间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 scope，如果它是全局的。
如果外部 scope 是nonlocal ，则使用 nonlocal 关键字代替 - 这是 Python 3.0 引入的。
然而，改变调用者 function 的 scope 并不是 Python 的前提，而是语言特性。
这是可以做到的。 但仅仅通过调用私有 C api（将“本地”值烘焙回快速局部变量），这绝对不是一个好习惯。
也可以通过魔法装饰器来实现，但装饰器必须重写内部 function 中的字节码 - 通过检索和更新校准器locals上的值来替换对“非本地”变量的每次访问，并且，在function - https 的结尾：//programtalk.com/python-examples/ctypes.pythonapi.PyFrame_LocalsToFast/
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地狱- 但是如果代理 class 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。 它应该很容易适应它来搜索局部变量以在调用堆栈上进行更改（以便在子子调用中所做的更改可以更改祖父母的本地人，就像在动态范围的语言中一样）
如问题中所述，无需将调用者上的变量声明为任何内容-它们必须是普通的局部变量。 However, this requires the declaration, on the decorated function, the variables I want to change on the caller scope as 'global', so that changing then will go through an object I can customize. 如果你连这个都做不到，你确实不得不求助于在装饰的 function 上重写字节码，或者使用为编写调试器而设置的钩子（在代码上设置“trace on”）。
注意，最近更改 locals() 的确切行为已指定给该语言 - 在 3.8、IIRC 之前 - 并且“ locals_to_fast ”似乎是一个足够稳定的 API - 但它可能会在未来发生变化。
# 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，将所有内容粘贴到 IPython shell 上：
In [121]: bleh()
original value
new value
（我可能会补充一点，测试感觉很奇怪，因为改变了局部变量的函数不需要任何装饰器，或者根本不需要对变量进行任何特殊声明）
好的，所以在坐了几个小时之后，我设法编写了一个解决方案，在处理这个问题时有一些主要的陷阱，我会在下面指出它们
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 += "d\x00\x00\x04U" # LOAD_CONST None, DUP_TOP, EXEC_STMT
init += "z" + struct.pack("H", len(self.f.func_code.co_code) + 4) #SETUP_FINALLY
fini = "Wd\x00\x00" # 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 += "d\x00\x00\x04UXd\x00\x00S" # 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 = "\x00\x00\x0b" + 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
所需的实际代码在class inline_func和一些导入中（也许您可以将它们设置为 class 的内部？我真的不确定）
那么这整件事是做什么的呢？ 好吧，它使strip_game和game的代码（几乎）相同，即：
有一些主要的陷阱使这样的事情发生，我将列出我遇到的一些问题：
compiler_nameop function 基于给定 function 的简单性优化命名空间查找，这意味着如果可以的话，它将优化名称查找到全局查找co_lnotab变量中解决了这个问题感谢@jsbueno 投入时间并将我指向 PyFrame_LocalsToFast。
PS 此解决方案适用于 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。
有没有一种方法可以使用python日志记录从调用方的范围进行打印
[英]Is there a way to use python logging to print from the scope of the caller
有没有办法像调用者所说的那样在被调用者中获取 function 参数？
[英]Is there a way to get the function parameters in the calle as the caller put it?
在函数/方法中改变字典并返回给调用者的首选方式？
[英]Preferred way of mutating dictionary inside function/method and returning to the caller?
在Python function中，有没有办法在调用方告诉参数的变量名？
[英]In a Python function, Is there a way to tell the argument's variable name on the caller side?
有没有办法让多个函数的调用者以纯函数的方式将函数引用转发给选定的函数？
[英]Is there a way for a caller of multiple functions to forward a function ref to selected functions in a purely functional way?
有没有办法使用Twilio python查找api打印输出并使用作为变量找到的调用者名称？
[英]Is there a way to use Twilio python lookup api print output and use the caller name found as variable?
声明:本站的技术帖子网页，遵循CC BY-SA 4.0协议，如果您需要转载，请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.