[Tutor] beginsWith multiple prefixes

[Alan Gauld]

"Kent Johnson" <kent37 at tds.net> wrote

>> You could also make this a method of a subclass of string if you 
>> prefer:
>>
>> class MyString(str):
>>  def beginswith(self, prefixes):
>>       for prefix in prefixes:
>>            if self.startswith(prefix):
>>               return prefix
>
> It's an appealing idea but the extra step of wrapping strings in
> MyString kind of takes the shine off of it. For example something 
> like
> this is awkward:
> for d in os.listdir():
>  d = MyString(d)
>  if d.beginswith(...):

I would write that as:

for d in os.listdir():
    if MyString(d).beginswith(....):

Which isn't that cumbersome. d is still available for
subsequent processing and acces to normal string
methods is still useful , as in:

for d in os.listdir():
    if MyString(d).upper().beginswith(....):

But it's a matter of taste I guess.

-- 
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld


>
> Some languages allow you to extend a built-in class, this technique
> works better there.
>
> Kent
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