Callable Primer

All code is in Python 3.



In [1]:

    
def a_function(*args, **kwargs):
    return 'Hello DjangoCon 2015!'



In [2]:

    
a_function()









    Out[2]:





'Hello DjangoCon 2015!'



In [3]:

    
lambda_function = lambda: 'Enjoying Austin?'



In [4]:

    
lambda_function()









    Out[4]:





'Enjoying Austin?'



In [5]:

    
class FirstClass:
    an_attribute = 'Have you visited any good restaurants?'

    def a_method(*args, **kwargs):
        self = args[0]
        return self.an_attribute



In [6]:

    
fc_obj = FirstClass()
fc_obj.a_method()









    Out[6]:





'Have you visited any good restaurants?'



In [7]:

    
class SecondClass(FirstClass):

    def __init__(self):
        """Dunder/Magic method to initialize a class"""
        self.an_attribute = "Easy Tiger, La Condessa and Lambert's are my favorites."



In [8]:

    
sc_obj = SecondClass()
sc_obj.a_method()









    Out[8]:





"Easy Tiger, La Condessa and Lambert's are my favorites."



In [9]:

    
class ThirdClass(SecondClass):

    def __call__(*args, **kwargs):
        """Dunder/Magic method to make object callable"""
        return "I like grabbing ice cream at Amy's, too."



In [10]:

    
tc_obj = ThirdClass()
tc_obj()









    Out[10]:





"I like grabbing ice cream at Amy's, too."



In [11]:

    
# callable is a Python built-in
callable(a_function)









    Out[11]:





True



In [12]:

    
callable(lambda_function)









    Out[12]:





True



In [13]:

    
callable(FirstClass)









    Out[13]:





True



In [14]:

    
callable(fc_obj)









    Out[14]:





False



In [15]:

    
callable(sc_obj)









    Out[15]:





False



In [16]:

    
callable(tc_obj)









    Out[16]:





True