Python defining Function

Question

I want to make a function that strips whitespace from a string, what I have so far is:

def stripped(x):
    x = x.replace('  ', '')

string = " yes   Maybe   So"

I want to just strip the space by doing this

string.stripped()

but I keep getting this error AttributeError: 'str' object has no attribute 'stripped'

what am I doing wrong I am guessing it is something simple I am just overlooking, thanks in advance.

You need to give the string to `stripped`. `stripped` isn't a string method. — Carcigenicate, Jun 22 '17 at 17:37
you want `stripped` to `return x` and then `string = stripped(string)` — castis, Jun 22 '17 at 17:37
Possible duplicate of [Implementing a custom string method](https://stackoverflow.com/questions/4519702/implementing-a-custom-string-method) — depperm, Jun 22 '17 at 17:38

Christian Dean · Accepted Answer · 2017-06-22T17:46:00.297

When you define your function, you Python creates a lone function object called stripped. It doesn't add your function to the builtin str object. You just

need to call your method on the string normally:

>>> def stripped(x):
    x = x.replace('  ', '')


>>> string = " yes   Maybe   So"
>>> stripped(string)
>>>

Note however string will not be modified, You need to return the result of x.replace() and assign it to string:

>>> def stripped(x):
    return x.replace('  ', '')

>>> string = " yes   Maybe   So"
>>> string = stripped(string)
>>> string
' yes Maybe So'
>>>

Note what your asking for is techinally possible. It is a monkey-patch however and shouldn't be used. But just for completeness:

>>> _str = str
>>> 
>>> class str(_str):
    def stripped(self):
        return self.replace('  ', '')


>>> string = str(" yes   Maybe   So")
>>> string.stripped()
' yes Maybe So'
>>>

Gotcha I didnt think I would have to return it, I wasnt understanding that properly, thanks for the help this works. I will accept as soon as I can. — Cannon, Jun 22 '17 at 17:44

score 0 · Answer 2 · answered Jun 22 '17 at 17:38

0

You can't add a method to an existing class like that. You could write a function that receives and returns a string:

def stripped(x):
    return x.replace('  ', '')

And the call it by passing your string:

s = " yes   Maybe   So"
s = stripped(s)

answered Jun 22 '17 at 17:38

Mureinik

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Brett Beatty · Answer 3 · 2017-06-22T17:45:47.757

-1

If you want all whitespace, not just spaces, you can do ''.join(string.split())

def stripped(string):
    return ''.join(string.split())

string = stripped(' yes   Maybe   So')

# But it would also handle this
string = stripped(' yes \n Maybe  So\n')
assert string == 'yesMaybeSo'

edited Jun 22 '17 at 17:45

answered Jun 22 '17 at 17:40

Brett Beatty

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While this does perhaps offer a better method, it doesn't answer the main question, which is probably why you got downvoted. (I didn't downvote). – Christian Dean Jun 22 '17 at 17:47

Python defining Function

3 Answers3