[Python-Dev] str.join, string.join (original) (raw)

Christian Tismer tismer@tismer.com
Tue, 11 Feb 2003 19:04:57 +0100

Hi Tim, pydev,

while fighting this conditional super thread, I stumbled over something about "".join, as it was used as an argument for reading LtoR.

Citing A. Koenig and Ahz: """ ','.join(lines)

Aahz> Many people (including me) think it's NOT Pythonic.

If I were trying to make code easy to understand for inexperienced programmers, I would write str.join(',', lines) instead of ','.join(lines). """

I have two observations:

  1. Through introduction of strings as class-like objects, new calling patterns are generated.

Unfortunately, this is the opposite as in the string module: str.join(',', lines) # vs. string.join(lines, ',')

What is now pythonic. Was it (a posteriori) a mistake to add join as a method to strings, since it creates a calling pattern that is incompatible with the string function?

Side remark: This error message is confusing:

str.join(" ") Traceback (most recent call last): File "", line 1, in ? TypeError: join() takes exactly one argument (0 given)

Well, the method is probably not well suited to be called by the class, only (expecting to be a method, always). But now it exists.

  1. Given the str "class", we could use it to make the string module absolutely redundant, since we can put all string constants into str now. So we would be able to use str.digits # instead of string.digits

Trying to make sense of 1) and 2), I get into trouble because of the inconsistent join issue.

What is the long-term way to make this pythonic again: Should "".join be dropped in favor of a class method which reads like the old string.join? Or should it be kept like today, exist as "".join(stuff) and str.join("", stuff), and string.join becomes deprecated?

ciao - chris

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