[Python-Dev] Usage of += on strings in loops in stdlib (original) (raw)

Steven D'Aprano steve at pearwood.info
Wed Feb 13 12:37:13 CET 2013

On 13/02/13 19:52, Larry Hastings wrote:

I've always hated the "".join(array) idiom for "fast" string concatenation --it's ugly and it flies in the face of TOOWTDI. I think everyone should use "x = a + b + c + d" for string concatenation, and we should just make that fast.

"".join(array) is much nicer looking than:

 # ridiculous and impractical for more than a few items
 array[0] + array[1] + array[2] + ... + array[N]

or:

 # not an expression
 result = ""
 for s in array:
     result += s

or even:

 # currently prohibited, and not obvious
 sum(array, "")

although I will admit to a certain fondness towards

 # even less obvious than sum
 map(operator.add, array)

and join has been the obvious way to do repeated concatenation of many substrings since at least Python 1.5 when it was spelled "string.join(array [, sep=" "]).

-- Steven

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