Fixed #34578 -- Made "join" template filter respect autoescape for joiner.

[rajeeshrp]

• If autoescape is off, join filter will not escape the joining string now.

[github-actions]

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[felixxm]

@rajeeshrp Thanks 👍 I left comments.

[felixxm]

@rajeeshrp Thanks 👍 Welcome aboard ⛵

I pushed small edits and squashed commits.

[shangxiao]

I was going to make a small suggestion unrelated to the ticket in the function but I'll wait until you've merged it and submit a PR separately 🤔

[felixxm]

I was going to make a small suggestion unrelated to the ticket in the function but I'll wait until you've merged it and submit a PR separately thinking

Please share 👀

[shangxiao]

Oh hm after your edit it doesn't really refactor that well but going on the previous version (and this was a thing in the original code so no criticism of rajeeshp here):

@register.filter(is_safe=True, needs_autoescape=True)
def join(value, arg, autoescape=True):
    """Join a list with a string, like Python's ``str.join(list)``."""
    try:
        if autoescape:
            data = conditional_escape(arg).join(conditional_escape(v) for v in value)
        else:
            data = arg.join(value)
    except TypeError:  # Fail silently if arg isn't iterable.
        return value
    return mark_safe(data)

The point is to use a generator expression instead of a material list:

• slight optimisation for what that's worth
• I strongly discourage the reassignment of variables (especially when there's a type change) as it can lead to brittle code

You could also "improve" if further with the data = <expr1> if <condition> else <expr2> expression 🤷‍♂️ ("improve" in this case is entirely subjective)

[felixxm]

The point is to use a generator expression instead of a material list:

A list comprehension is preferable here as str.join() converts to list internally anyway. It is better performance to provide a list up front.

• https://stackoverflow.com/questions/9060653/list-comprehension-without-in-python/9061024#9061024
• Add rule to recommend str.join takes a list comp over generator adamchainz/flake8-comprehensions#156

[felixxm]

I strongly discourage the reassignment of variables (especially when there's a type change) as it can lead to brittle code

Agreed 👍

[shangxiao]

Well TIL! ❤️