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

Sunday, 30 July 2017

This has always confused me. It seems like this would be nicer:

my_list = ["Hello", "world"]
print(my_list.join("-"))
# Produce: "Hello-world"

Than this:

my_list = ["Hello", "world"]
print("-".join(my_list))
# Produce: "Hello-world"

Is there a specific reason it is like this?

Answer

It's because any iterable can be joined, not just lists, but the result and the "joiner" are always strings.

For example:

import urllib2
print('\n############\n'.join(
    urllib2.urlopen('http://data.stackexchange.com/users/7095')))

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