Python检查字符串是否在dir（）中，以及是否将该字符串转换为方法/函数调用

Question

How do I turn a user generated string into a method or function call in Python2.7? Can you search the dir(object) to see if the method/function exists and then call that method?

Answer 1

It is best to just try to call the method, if it's not there it will throw an exception, which you can handle.

>>> try: obj.a_method()
... except AttributeError: print 'No method a_method in this object'
... 
No method a_method in this object
>>> 

Answer 2

You could try something like:

ui = input("Try something: ")
if ui in dir():
    func = eval(ui)
    func()

For example:

>>> def test():
    return "foo"

>>> if "test" in dir():
    func = eval("test")
    func()


'foo'

Answer 3

Function names are just attributes, so you can do this:

try:
    getattr(object, methodname)()
except AttributeError as e:
    print 'Method %s not found or not callable!'%methodname

Answer 4

You can use globals it returns module's __dict__

def command_1():                                                                
    print "You are in command 1"                                                

def command_2():                                                                
    print "You are in command 2"                                                

def default():                                                                  
    print "Can't find your command"                                             

func = raw_input("ENTER YOUR COMMAND: ")                                        
your_func = globals().get(func, None)                                           
if your_func is None:                                                                                                                                       
    your_func = default                                                         

your_func() 

Output:

ENTER YOUR COMMAND: command_1
You are in command 1

or

ENTER YOUR COMMAND: aaa
Can't find your command