What is callable() in Python?
callable() is a built-in method in Python that checks if a passed object appears to be
- The type that demonstrates callability, such as a function or a method.
- An instance of a class with a
__call__method.
Syntax
callable(object)
Parameters
callable() only takes in a single parameter: the object to be checked.
Return value
The function returns True if the object appears to be callable. Otherwise, it returns False.
Note: The function may have false positives. This means the call to the object might fail even if
callable()returnsTrue. However, if the function returnsFalse, the call to the object will always fail.
Example code 1
# Object 1
x = 10
def sampleFunction():
print("Hello World!")
# Object 2
y = sampleFunction
# Checking if Object 1 and Object 2 appear to be callable
print("Object 1: ", callable(x))
print("Object 2: ", callable(y))
# Checking if Object 2 is truly callable
y()In the example above, the callable() function correctly indicates the callability of the two objects.
Example code 2
# creating classes
class sampleClass1:
def __call__(self):
print("This is sample class one!")
class sampleClass2:
def sampleFunction():
print("This is sample class two!")
# creating object 1
x = sampleClass1()
print("Object 1: ", callable(x))
x()
# checking if sampleClass2 is callable
print("sampleClass2: ", callable(sampleClass2))
# creating object 2
y = sampleClass2()
y() # This will throw an error In this example, the instance of the sampleClass1 class appears to be callable and is actually callable.
On the other hand, the sampleClass2 class appears to be callable, but the instance of the class is not callable, and an error is thrown.
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