Python callable()

The callable() function in Python returns True if the object passed appears to be callable. Otherwise, it returns False.

callable() Syntax 

The syntax of the callable() method is 

callable(object)

callable() Parameters

The callable() method can take only one argument, i.e., an object.

callable() Return Value

The callable() function returns

• True – if the object appears callable
• False – if the object is not callable.

Note: There may be few cases where callable() returns True, but the call to the object may fail. But in case if callable() returns False, the calling object will never succeed.

Example 1: How does callable() works?

Here, the object number is not callable. And, the object getData appears to be callable (but may not be callable).

# returns false as the object of integer is not callable
number = 10
print(callable(number))

def getData():
  print("Hello World")

# returns true as the variable is callable
obj = getData
print(callable(obj))

Output

False
True

Example 2: When an Object is callable 

The built-in callable() method checks if the argument passed is either of the below two cases:

• An instance of a class having a __call__ method.
• It is of a type that indicates callability, such as in functions, methods, etc. or has a non-null tp_call (c struct) member.

# Python program to demonstrate callable()
class Test:
  def __call__(self):
    print('Hello World !!!')

# Suggests that Test class is callable and returns True
print(callable(Test))

# This proves that class is callable
TestObject = Test()
TestObject()

Output

True
Hello World !!!

Example 3: When an Object is NOT callable 

The callable() method returns True, suggesting that the Test class is callable, but the instance of Test is not callable, and it returns a TypeError: ‘Test’ object is not callable

# Python program to demonstrate NOT callable()
class Test:
  def printdata(self):
    print('Hello World !!!')

# Suggests that Test class is callable and returns True
print(callable(Test))

# The object will be created but returns error while calling
TestObject = Test()
TestObject()

Output

True

Traceback (most recent call last):
  File "c:\Projects\Tryouts\main.py", line 11, in <module>
    TestObject()
TypeError: 'Test' object is not callable