Python Ellipsis vs pass

In Python, “Ellipsis” and “pass” are two different concepts with distinct purposes. Let’s clarify the difference between “Python Ellipsis” and “pass”:

Ellipsis (...): The ellipsis (...) is a special built-in object in Python. It is primarily used as a slice notation placeholder when working with NumPy arrays or custom classes. It can also be used as a placeholder in function arguments. The primary use of ellipsis is to represent a slice of an array when you don’t want to specify all the dimensions.

my_list = [1, 2, 3, 4, 5]
# Using Ellipsis for slicing
partial_list = my_list[1:...]  # equivalent to my_list[1:]
print(partial_list)  # Output: [2, 3, 4, 5]

In function arguments:

def my_function(arg1, arg2, ...):
    # Function implementation here
    pass

pass: pass is a keyword in Python used as a no-operation or null operation statement. It is used when a statement is syntactically required but you don’t want to perform any operation. The “pass” statement does nothing when executed. It is typically used as a placeholder for future code or to create empty code blocks that might be filled in later.

For example, when defining an empty function or loop:

def my_function():
    pass  # Placeholder for the function implementation

for item in my_list:
    # Some processing here
    pass  # Placeholder for the loop body

Using pass allows you to create valid code that doesn’t raise syntax errors while leaving the implementation empty or to be added later.

Python Ellipsis vs pass example

Let’s provide some examples to illustrate the usage of “Ellipsis” and “pass” in Python:

Example using Ellipsis (...):

# Example 1: Ellipsis in slicing
my_list = [1, 2, 3, 4, 5]
partial_list = my_list[1:...]  # Using Ellipsis for slicing
print(partial_list)  # Output: [2, 3, 4, 5]

# Example 2: Ellipsis in function arguments
def my_function(arg1, arg2, ...):
    # Function implementation here
    print(arg1, arg2)

my_function(10, 20)  # Output: 10 20

We used the Ellipsis to represent the missing end index in the slice, effectively taking the elements from index 1 to the end of the list.

Example using pass:

my_list = [1, 2, 3, 4, 5]

# Example 1: Using pass in a loop
for item in my_list:
    print(f"Processing item: {item}")

# Example 2: Using pass in an empty function
def empty_function():
    return None  # Placeholder return statement

# Example 3: Using pass in a conditional block
condition = False
if condition:
    print("Condition is True")
else:
    print("Condition is False")

Output:

In summary, “Ellipsis” is not a standalone statement but a built-in object used as a placeholder in specific contexts, while “pass” is a standalone statement used as a no-operation placeholder in various situations within the code. They serve different purposes and have distinct syntax usages.

Note: IDE: PyCharm 2021.3.3 (Community Edition)

Windows 10

Python 3.10.1

All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.