String replace with return value?

[Fredrik Lundh]

Duncan Booth wrote:

>> How can I do a "".replace operation which tells me if anything was
>> actually replaced?
>> Right now I am doing something like:
>>
>> if searchTerm in text:
>>      text = text.replace( searchTerm, 'other' )
>
> Try:
>
> newtext = oldtext.replace(searchTerm, 'other')
> if newtext is oldtext:
>    print "nothing changed"
> else:
>    print "modified text"
>
> You can almost certainly get away with using 'is' here since if replace
> doesn't replace anything it simply returns the original string

depends on how you define "if anything was actually replaced", of course:

>>> mytext = "hello"

>>> mytext is mytext.replace("l", "l")
False
>>> mytext == mytext.replace("l", "l")
True

>>> mytext is mytext.replace("x", "x")
True
>>> mytext == mytext.replace("x", "x")
True

</F>