Pyhon 2.x or 3.x, which is faster?

[BartC]

On 12/03/2016 10:06, alister wrote:
> On Fri, 11 Mar 2016 22:24:45 +0000, BartC wrote:
>
>> On 11/03/2016 21:59, Mark Lawrence wrote:
>>> On 11/03/2016 18:57, BartC wrote:
>>
>>> def test():
>>>       s=""
>>>       for i in range(10000000):
>>>           s+="*"
>>>       print (len(s))
>>>
>>> test()
>>
>>> The minor snag that you might like to correct with your microbenchmark,
>>> which any experienced Python programmer knows, is that you *NEVER,
>>> EVER*
>>> create strings like this.
>>
>> Why not? Chris said his version runs much faster (even allowing for
>> different machines), and might have a special optimisation for it.
>>
>> And I think it can be optimised if, for example, there are no other
>> references to the string that s refers to.
>>
>> So what's wrong with trying to fix it rather that using a workaround?
>
> because the "workarround" is not a workarround it is the correct way to
> do it
> the code above is a workarround for somone who does not know the pythonic
> method to do this
>
> S= "*"*10000000

This is a benchmark that measures the cost of adding to a string a 
character at a time.

In practice the final length of the string is not known, and the 
characters added at each stage are not known.

Although the strings won't usually be that big; the benchmark 
exaggerates here to highlight a possible issue with += on strings. And 
it worked, as there can be big difference with or without the += 
optimisation in place.

It also showed a possible bug or problem with PyPy.

You can't demonstrate all this by just writing s="*"*10000000.

-- 
Bartc