使用内置的getattr函数按名称获取对象的属性。根据需要修改名称。

obj.spam = 'eggs'
name = 'spam'
getattr(obj, name)  # returns 'eggs'

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

您也可以使用collections模块中的namedtuple来代替字典，这使得访问更容易。

例如:

# using dictionary
variables = {}
variables["first"] = 34
variables["second"] = 45
print(variables["first"], variables["second"])

# using namedtuple
Variables = namedtuple('Variables', ['first', 'second'])
v = Variables(34, 45)
print(v.first, v.second)

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

setattr()方法设置指定对象的指定属性的值。

语法是这样的-

setattr(object, name, value)
Example –

setattr(self,id,123)

它等价于self。Id = 123

正如您可能已经观察到的，setattr()期望将一个对象与值一起传递，以生成/修改一个新属性。

我们可以将setattr()与一个解决方案一起使用，以便能够在模块中使用。这里怎么——

import sys
x = "pikachu"
value = 46
thismodule = sys.modules[__name__]
setattr(thismodule, x, value)
print(pikachu)

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。