Creating a ref to a string ?

[StrikerX11]

Hi,
How can i create a ref to a string ? it doesn't work like lists :S

List : (IDs are the same!)

>>> li=[1, 2, 3, 4, 5]
>>> li_ref=li
>>> id(li)
13545800
>>> id(li_ref)
13545800
>>> li.pop()
5
>>> li
[1, 2, 3, 4]
>>> id(li)
13545800
>>> li_ref
[1, 2, 3, 4]
>>> id(li_ref)
13545800

String : (the ID of each is different!)

>>> s="Hello, "
>>> s_ref=s
>>> id(s)
13553952
>>> id(s_ref)
13553952
>>> s += "World!"
>>> s
'Hello, World!'
>>> s_ref
'Hello, '
>>> id(s)
13560752
>>> id(s_ref)
13553952

So any ideas ?

[woooee]

>>> a=b="test"
>>> print a
test
>>> print b
test
>>> id(a)
3084724384L
>>> id(b)
3084724384L

Or convert the string to a list and then back to a string when you are finished.

[paddy3118]

Strings are known as immutable. You cannot take a string object and change its value without creating another string, so although you can have two names refer to the same string object, when you create a new string object and assign it to one of the names, the other name is still referring to the original object.

You could embed a string in a list and have two names refer to the list. Then changing the string in the list will be seen via both names
i.e:

s1 = ["Spam"]
s2 = s1
s2[0] = "Ham"
assert s1 == ["Ham"]

- Paddy.

[jrcagle]

or create a class that looks like a string:

class MyString(object):

    def __init__(self, string):
        self.value = string

    def __str__(self):
        return self.value

    # I think strings ought to support index assignment.  So my strings will.
    def __setitem__(self, index, item):
        self.value = self.value[:index] + item + self.value[index+1:]

    def __getitem__(self, index):
        return self.value[index]

    def __mul__(self, multiple):
        return self.value * multiple

    def __add__(self, addend):
        return self.value + addend

    def __iadd__(self, addend):
        self.value += addend
        return self
  
   # add more methods to make it even more string-like.

a = MyString("Hi!")
print a, id(a)
print a*5, id(a)
a += "whoa!"
print a, id(a)
print a[1], id(a)
a[2] = "?"
print a, id(a)

---
Hi! 12077744
Hi!Hi!Hi!Hi!Hi! 12077744
Hi!whoa! 12077744
i 12077744
Hi?whoa! 12077744

But now this raises the question: why do you want such a thing?

Jeff

[paddy3118]

Check out the mutable string class past the middle of this page

[StrikerX11]

Sorry for being late,
Thanks guyz, that was helpful

[jrcagle]

Ooh, the MutableString class was interesting. Thanks, paddy. Of course, the various caveats on that page were not very encouraging...:D

Jeff