[Tutor] str.replace error

[Mats Wichmann]

On 4/25/19 10:29 PM, Steven D'Aprano wrote:
> On Thu, Apr 25, 2019 at 10:46:31AM -0700, Roger Lea Scherer wrote:
> 
>> with open('somefile') as csvDataFile:
>>     csvReader = csv.reader(csvDataFile)
>>     for row in range(100):
>>         a = "Basic P1"
>>         str.replace(a, "")
>>         print(next(csvReader))
> 
> 
> I'm not quite sure what you expected this to do, but you've 
> (deliberately? accidently?) run into one of the slightly advanced 
> corners of Python: unbound methods. 

accidentally, I believe.

notice that the way the Python 3 page on string methods is written, you
_could_ read it as you are to use the literal 'str' but in fact you are
expected to substitute in the name of your string object.

For this specific case:
===
str.replace(old, new[, count])

    Return a copy of the string with all occurrences of substring old
replaced by new. If the optional argument count is given, only the first
count occurrences are replaced.
===

So for the example above you're expected to do (without changing the
range call, which has been commented on elsewhere: you should just
iterate directly over the reader object, that's the way it's designed):

for row in range(100):
    a = "Basic P1"
    row.replace(a, "")

and then hopefully actually do something with the modified 'row', not
just go on to the next iteration and throw it away...