这不是个好主意。如果要访问全局变量，可以使用globals()。

>>> a = 10
>>> globals()['a']
10

如果想要访问局部作用域内的变量，可以使用locals()，但不能为返回的dict赋值。

更好的解决方案是使用getattr或将变量存储在字典中，然后按名称访问它们。

你必须使用globals()内置方法来实现这种行为:

def var_of_var(k, v):
    globals()[k] = v

print variable_name # NameError: name 'variable_name' is not defined
some_name = 'variable_name'
globals()[some_name] = 123
print(variable_name) # 123

some_name = 'variable_name2'
var_of_var(some_name, 456)
print(variable_name2) # 456

大家的共识是使用字典来进行查询-请参阅其他答案。在大多数情况下，这是一个好主意，然而，这产生了许多方面:

您将自己负责这个字典，包括垃圾收集(indict变量)等。 变量变量没有局部性或全局性，这取决于字典的全局性 如果要重命名变量名，则必须手动执行 然而，你要灵活得多，例如: 您可以决定覆盖现有变量或… ．.． 选择实现const变量 针对不同类型的重写引发异常 等。

也就是说，我已经实现了一个变量变量管理器类，它提供了上面的一些想法。它适用于python 2和3。

你可以这样使用这个类:

from variableVariablesManager import VariableVariablesManager

myVars = VariableVariablesManager()
myVars['test'] = 25
print(myVars['test'])

# define a const variable
myVars.defineConstVariable('myconst', 13)
try:
    myVars['myconst'] = 14 # <- this raises an error, since 'myconst' must not be changed
    print("not allowed")
except AttributeError as e:
    pass

# rename a variable
myVars.renameVariable('myconst', 'myconstOther')

# preserve locality
def testLocalVar():
    myVars = VariableVariablesManager()
    myVars['test'] = 13
    print("inside function myVars['test']:", myVars['test'])
testLocalVar()
print("outside function myVars['test']:", myVars['test'])

# define a global variable
myVars.defineGlobalVariable('globalVar', 12)
def testGlobalVar():
    myVars = VariableVariablesManager()
    print("inside function myVars['globalVar']:", myVars['globalVar'])
    myVars['globalVar'] = 13
    print("inside function myVars['globalVar'] (having been changed):", myVars['globalVar'])
testGlobalVar()
print("outside function myVars['globalVar']:", myVars['globalVar'])

如果你希望只允许覆盖相同类型的变量:

myVars = VariableVariablesManager(enforceSameTypeOnOverride = True)
myVars['test'] = 25
myVars['test'] = "Cat" # <- raises Exception (different type on overwriting)

Python中的变量

"""
<?php
$a = 'hello';
$e = 'wow'
?>
<?php
$$a = 'world';
?>
<?php
echo "$a ${$a}\n";
echo "$a ${$a[1]}\n";
?>
<?php
echo "$a $hello";
?>
"""

a = 'hello'  #<?php $a = 'hello'; ?>
e = 'wow'   #<?php $e = 'wow'; ?>
vars()[a] = 'world' #<?php $$a = 'world'; ?>
print(a, vars()[a]) #<?php echo "$a ${$a}\n"; ?>
print(a, vars()[vars()['a'][1]]) #<?php echo "$a ${$a[1]}\n"; ?>
print(a, hello) #<?php echo "$a $hello"; ?>

输出:

hello world
hello wow
hello world

使用globals()、locals()或vars()将产生相同的结果

#<?php $a = 'hello'; ?>
#<?php $e = 'wow'; ?>
#<?php $$a = 'world'; ?>
#<?php echo "$a ${$a}\n"; ?>
#<?php echo "$a ${$a[1]}\n"; ?>
#<?php echo "$a $hello"; ?>

print('locals():\n')
a = 'hello'
e = 'wow'
locals()[a] = 'world'
print(a, locals()[a])
print(a, locals()[locals()['a'][1]])
print(a, hello)

print('\n\nglobals():\n')
a = 'hello'
e = 'wow'
globals()[a] = 'world'
print(a, globals()[a])
print(a, globals()[globals()['a'][1]])
print(a, hello)

输出:

locals():

hello world
hello wow
hello world


globals():

hello world
hello wow
hello world

奖励(从字符串创建变量)

# Python 2.7.16 (default, Jul 13 2019, 16:01:51)
# [GCC 8.3.0] on linux2

创建变量并解包元组:

g = globals()
listB = []
for i in range(10):
    g["num%s" % i] = i ** 10
    listB.append("num{0}".format(i))

def printNum():
    print "Printing num0 to num9:"
    for i in range(10):
        print "num%s = " % i, 
        print g["num%s" % i]

printNum()

listA = []
for i in range(10):
    listA.append(i)

listA = tuple(listA)
print listA, '"Tuple to unpack"'

listB = str(str(listB).strip("[]").replace("'", "") + " = listA")

print listB

exec listB

printNum()

输出:

Printing num0 to num9:
num0 =  0
num1 =  1
num2 =  1024
num3 =  59049
num4 =  1048576
num5 =  9765625
num6 =  60466176
num7 =  282475249
num8 =  1073741824
num9 =  3486784401
(0, 1, 2, 3, 4, 5, 6, 7, 8, 9) "Tuple to unpack"
num0, num1, num2, num3, num4, num5, num6, num7, num8, num9 = listA
Printing num0 to num9:
num0 =  0
num1 =  1
num2 =  2
num3 =  3
num4 =  4
num5 =  5
num6 =  6
num7 =  7
num8 =  8
num9 =  9

如果你不想使用任何对象，你仍然可以在当前模块中使用setattr():

import sys
current_module = module = sys.modules[__name__]  # i.e the "file" where your code is written
setattr(current_module, 'variable_name', 15)  # 15 is the value you assign to the var
print(variable_name)  # >>> 15, created from a string

我回答的问题如何得到一个变量的值给定它的名字在一个字符串? 这是一个带有问题链接的副本。(编者注:它现在被关闭为“如何通过(字符串)名称选择变量?”的副本?)

如果所讨论的变量是对象的一部分(例如类的一部分)，则可以使用hasattr、getattr和setattr函数来实现这一点。

例如，你可以有:

class Variables(object):
    def __init__(self):
        self.foo = "initial_variable"

    def create_new_var(self, name, value):
        setattr(self, name, value)

    def get_var(self, name):
        if hasattr(self, name):
            return getattr(self, name)
        else:
            raise "Class does not have a variable named: " + name

然后你可以这样做:

>>> v = Variables()
>>> v.get_var("foo")
'initial_variable'

>>> v.create_new_var(v.foo, "is actually not initial")
>>> v.initial_variable
'is actually not initial'