Chris Angelico added the comment:
CPython also knows the length of a string, which means that len(s) is a fast
operation. I wouldn't expect anyone to rewrite len() as:
def get_string_length(s):
length=0
for ch in s:
length+=1
return length
even though that works. No, we have a built-in function that's able to simply
query the header. (Via a special method, but it's still ultimately the same
thing.)
The only other use-case that I have at the moment relates to a query on
python-list about a broken MySQL, which was unable to handle astral characters.
With a simple and fast way to query the string's width, this could have been
checked for at practically zero cost; as it is, he had to scan all his strings
to find out what was in them. It's not something that's of immense value, but
it's a handy introspection, and one that should cost little or nothing to
provide.
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue17629>
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