th 357 - Python Programming: Why using __lt__ is better than __cmp__

Python Programming: Why using __lt__ is better than __cmp__

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th?q=  lt   Instead Of   cmp   - Python Programming: Why using __lt__ is better than __cmp__

If you are a programmer, you might have heard about Python, the high-level programming language known for its simplicity and readability. Python has gained immense popularity in recent years, thanks to its ability to build robust and scalable applications with ease. One of the most critical aspects of programming in Python is understanding how to compare objects. There are two ways to compare objects in Python – using the __lt__ and __cmp__ methods.

Here’s the catch: While both __lt__ and __cmp__ methods enable programmers to compare objects, using __lt__ is now considered better than using __cmp__. Why is this so, you might ask? Well, the reason is simple – the __cmp__ method is an older feature that is now being phased out of the language.

If you want to write clean, efficient and up-to-date code in Python, it’s crucial that you learn how to use the __lt__ method instead. Read on to find out why using __lt__ is better than __cmp__, and why you should make the switch today.

By the end of this article, you’ll understand the advantages of using __lt__ over __cmp__ and how to implement it in your code. So, let’s dive deeper and explore why you should embrace the use of __lt__ and become a better Python programmer today!

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“__lt__ Instead Of __cmp__” ~ bbaz


Python is a popular and widely used programming language that is easy to learn and use. It provides numerous features and functionalities that have made it a go-to language for developers. One such feature is the ability to compare values, which is useful when sorting items or performing other operations that require comparison. In Python, there are two methods for value comparison: __cmp__ and __lt__. In this blog post, we will compare these two methods and explain why using __lt__ is generally better than using __cmp__.

Understanding the difference between __cmp__ and __lt__

Before we dive into the comparison, it’s important to understand what these two methods do. The __cmp__ method is used to compare two values and returns an integer value based on the comparison result. On the other hand, the __lt__ method is used to compare two values and returns a Boolean value (True or False) based on whether the first value is less than the second value.

The problem with __cmp__

While the __cmp__ method can be useful in certain situations, it has several limitations that make it less than ideal. For example, the return value of __cmp__ is limited to -1, 0, and 1, which can be cumbersome to work with. Additionally, Python 3.x doesn’t support __cmp__, making it a less future-proof solution.

The benefits of using __lt__

In contrast, __lt__ has several benefits that make it a better choice for value comparison. First, it returns a Boolean value, which is easier to work with than an integer value. Second, it is more flexible and allows for greater customization of comparison behavior. Finally, it is supported by both Python 2.x and 3.x, making it a more future-proof solution.

Comparing the syntax of __cmp__ and __lt__

__cmp__ __lt__
def __cmp__(self, other):    return cmp(self.value, other.value)
def __lt__(self, other):    return self.value < other.value

Explanation of table

The table above shows the syntax for __cmp__ and __lt__. As you can see, the syntax for __cmp__ requires the use of the built-in cmp() function, while the syntax for __lt__ uses only the less than operator (<). This makes the code written with __lt__ cleaner and easier to read.

Using __lt__ in practice

Let’s take a look at an example of how to use __lt__ in practice. Suppose we have a list of objects that we need to sort based on a certain criterion, such as their age. We could define a class with an __lt__ method that compares the age of two objects:

class Person:    def __init__(self, name, age): = name        self.age = age    def __lt__(self, other):        return self.age < other.age

Once we’ve defined this class, we can use Python’s built-in sorting function to sort a list of Person objects based on age:

people = [Person('Alice', 25), Person('Bob', 18), Person('Charlie', 30)]sorted_people = sorted(people)

In this example, the list of people is sorted based on their age using the __lt__ method.


While both __cmp__ and __lt__ can be used for value comparison in Python, __lt__ is generally the better choice. It is more flexible, easier to read and write, and supported by both Python 2.x and 3.x. If you’re using Python and need to compare values, we recommend using __lt__ instead of __cmp__ to ensure your code is future-proof and easy to work with.

Thank you for taking the time to read our article about why using __lt__ is better than __cmp__ when programming in Python. We hope that it has provided some valuable insights and information that you can use in your future coding endeavors.

As we discussed, the __cmp__ function was used in earlier versions of Python to compare objects. However, with the introduction of the __lt__ function in later versions, there are several advantages to using this method instead. Not only is it simpler and easier to implement, but it also helps to prevent potential errors and inconsistencies that can arise when using __cmp__.

If you are new to Python programming or simply looking to improve your skills, learning to use __lt__ effectively is a great step. By understanding the key differences between __lt__ and __cmp__, you will be able to write more efficient and effective code that is less susceptible to potential issues.

Again, thank you for taking the time to read our article. We hope that you have found it informative and helpful in your journey as a Python programmer. If you have any questions or comments, please feel free to leave them below. We would love to hear your thoughts and perspectives on this important topic.

People also ask about Python Programming: Why using __lt__ is better than __cmp__?

  1. What is the difference between __lt__ and __cmp__ in Python programming?
  2. The __lt__ method is used to implement the less than comparison operator in Python, whereas the __cmp__ method is used to compare two objects.

  3. Why is it recommended to use __lt__ instead of __cmp__?
  4. The __lt__ method is recommended over __cmp__ because it is simpler and more efficient. The __lt__ method only needs to return a boolean value, whereas __cmp__ must return -1, 0, or 1 to indicate less than, equal to, or greater than, respectively.

  5. Can you provide an example of using __lt__ in Python?
  6. Sure! Here is an example:

  • Create a class named Person with a name and age attribute.
  • Define the __lt__ method to compare Person objects based on their ages.
  • Create two Person objects and compare them using the less than operator.
class Person:    def __init__(self, name, age): = name        self.age = age        def __lt__(self, other):        return self.age < other.ageperson1 = Person('Alice', 25)person2 = Person('Bob', 30)print(person1 < person2) # Output: True