Why is it string.join(list) instead of list.join(string)?

The reason for str.join(iterable) rather than list.join(str) is based on the fact that join() is used to concatenate elements in the iterable with a separator, and the separator is part of the string.

Here's why str.join(iterable) is more intuitive:

    Concept of Concatenation: When you're concatenating strings with a separator, you're essentially joining them together. The separator is a string that you want to insert between the elements of the iterable. This concept aligns with the idea of joining elements with a separator.

    Consistency with Other String Methods: Python is designed to be consistent and intuitive. Many string methods, such as split(), replace(), and format(), involve manipulating the string itself, not the other way around. So, join() follows the same pattern.

Here's an example to illustrate:

python

# Using str.join(iterable)
words = ["Hello", "World", "Python"]
separator = " "
result = separator.join(words)
print(result)  # Output: "Hello World Python"

# Using str.replace(old, new)
sentence = "Hello, old friend!"
new_sentence = sentence.replace("old", "new")
print(new_sentence)  # Output: "Hello, new friend!"

Notice how both join() and replace() methods take the element (or substring) to be manipulated as an argument on which the method is called.

While it might seem counterintuitive at first, this design choice promotes a consistent and intuitive approach to working with string manipulation methods in Python.