Python type() Function

Python’s built-in type() function has two purposes. First, you can pass an object as an argument to check the type of this object. Second, you can pass three arguments—name, bases, and dict—to create a new type object that can be used to create instances of this new type.

Usage

Learn by example! Here’s an example on how to use the type() built-in function.

First, here’s how to use the type() function with one argument to check the type of a given object:

>>> type(42)
<class 'int'>
>>> type('Finxter')
<class 'str'>

Second, you can pass three arguments name, bases, and dict to create a new type:

>>> porsche = type('Car', (object,), {'speed': 100, 'electric':False})
>>> porsche
<class '__main__.Car'>
>>> porsche.speed
100
>>> porsche.electric
False

Let’s dive deeper into the powerful type() function to learn about it’s powerful features and usages!

Video type()

Let’s dive into the syntax of type() :

• Syntax type() with one argument to check class of object
• Syntax type() with three arguments to create new instance

Syntax type() with One Argument to Check Class of Object

Syntax: 
type(object)         # Returns class representation of object

An example is the following:

>>> type(42)
<class 'int'>
>>> type('Finxter')
<class 'str'>

In both cases, a string representation of the object’s class is returned.

Syntax type() with Three Arguments to Create New Instance

Syntax: 
type(name, bases, dict)         # Create a new instance with class name, base classes as defined in bases, and initial attributes as defined in dict

An example is the following:

>>> porsche = type('Car', (object,), {'speed': 100, 'electric':False})
>>> porsche
<class '__main__.Car'>
>>> porsche.speed
100
>>> porsche.electric
False

If you want to create another instance of the class car, you’d need to do some copy&paste work:

>>> tesla = type('Car', (object,), {'speed': 100, 'electric': True})
>>> tesla.electric
True

To avoid this, you could also create a new lambda function to one-linerize the object creation process with type():

>>> new_car = lambda attributes: type('Car', (object,), attributes)
>>> porsche = new_car({'speed':100, 'electric': False})
>>> tesla = new_car({'speed': 100, 'electric': True})
>>> porsche.electric
False
>>> tesla.electric
True

Interactive Shell Exercise: Understanding type()

Consider the following interactive code:

Exercise: Which type does the porsche instance have? Run to check!

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Summary

Python’s built-in type() function has two purposes.

• First, you can pass an object as an argument to check the type of this object.
• Second, you can pass three arguments—name, bases, and dict—to create a new type object that can be used to create instances of this new type.

First, here’s how to use the type() function with one argument to check the type of a given object:

>>> type(42)
<class 'int'>
>>> type('Finxter')
<class 'str'>

Second, you can pass three arguments name, bases, and dict to create a new type:

>>> porsche = type('Car', (object,), {'speed': 100, 'electric':False})
>>> porsche
<class '__main__.Car'>
>>> porsche.speed
100
>>> porsche.electric
False

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