你必须要了解了知识-python反射机制

a = "12 + 43"
b = eval(a)
print(b)

a = "print(12 + 43); print(1111)"
b = eval(a)
print(b)

# 输出：
Traceback (most recent call last):
  File "xxxx.py", line 10, in <module>
    b = eval(a)
  File "<string>", line 1
    print(12 + 43); print(1111)
                  ^
SyntaxError: invalid syntax

a = 1
b = eval("a = 21")
print(b)

b = exec("aa = 21")
print(b)      # None，exec返回值为None
print(aa)    # 21，exec执行了赋值语句，并定义了aa变量

a = '''ret = []
for i in range(10):
    ret.append(i)'''
exec(a)
print(ret)   # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

# 导入模块
exec("import config")
print(config.KEYWORD)

# 动态创建类
class Base:
    def __init__(self):
        print("Base")

a = "Base"
exec(a+"()")

class Base:
    def __init__(self):
        print("Base")

    def test(self):
        print("test")
        return "Base::test"

b = eval("a.test()")
print(b)

def hasattr(*args, **kwargs): # real signature unknown
    """
    Return whether the object has an attribute with the given name.

    This is done by calling getattr(obj, name) and catching AttributeError.
    """
    pass

def has_attr(obj, name):
    try:
        eval("obj.%s()" % name)
        return True
    except AttributeError as e:
        return False
a = Base()
if has_attr(a, "test"):
    eval("a.test()")

# 输出：
Base
test
test

def getattr(object, name, default=None): # known special case of getattr
    """
    getattr(object, name[, default]) -> value

    Get a named attribute from an object; getattr(x, 'y') is equivalent to x.y.
    When a default argument is given, it is returned when the attribute doesn't
    exist; without it, an exception is raised in that case.
    """
    pass

a = Base()
if hasattr(a, "test"):
    func = getattr(a, "test")
    func()

# 输出：
Base
test

def setattr(x, y, v): # real signature unknown; restored from __doc__
    """
    Sets the named attribute on the given object to the specified value.

    setattr(x, 'y', v) is equivalent to ``x.y = v''
    """
    pass

class Base:
    def __init__(self):
        self.name = "name"

a = Base()
setattr(a, "name", "zhangsan")
print(a.name)                    # 改变原有属性的值

setattr(a, "age", 32)
print(getattr(a, "age"))      # 新增不存在的属性，并设置值

def __import__(name, globals=None, locals=None, fromlist=(), level=0): # real signature unknown; restored from __doc__
    """
    __import__(name, globals=None, locals=None, fromlist=(), level=0) -> module

    Import a module. Because this function is meant for use by the Python
    interpreter and not for general use, it is better to use
    importlib.import_module() to programmatically import a module.

    The globals argument is only used to determine the context;
    they are not modified.  The locals argument is unused.  The fromlist
    should be a list of names to emulate ``from name import ...'', or an
    empty list to emulate ``import name''.
    When importing a module from a package, note that __import__('A.B', ...)
    returns package A when fromlist is empty, but its submodule B when
    fromlist is not empty.  The level argument is used to determine whether to
    perform absolute or relative imports: 0 is absolute, while a positive number
    is the number of parent directories to search relative to the current module.
    """
    pass

a = __import__("config")
print(a.KEYWORD)

# function.py

def comm_function():
    print("test_module")

a = __import__("comm.function")
a.comm_function()

Traceback (most recent call last):
  File "xxx.py", line 10, in <module>
    print(a.comm_function())
AttributeError: module 'comm' has no attribute 'comm_function'

a = __import__("comm.function", fromlist=True)
print(a.__name__)
a.comm_function()

# 输出：
comm.function
test_module