Python 2.2a4: Problems with overloading __str__ in subclasses of str

[Andreas.Trawoeger]

Hi!

I just ran into a strange problem with Python 2.2a4. I would like to write
a class that behaves like an string only with the difference that it
displays the string in hex.
In Python 2.2a4 this should be possible by subclassing str and overloading
__repr__ and __str__ :

from binascii import b2a_hex

class octetstring(str):
    def __repr__(self):
        return b2a_hex(str(self))
    def __str__(self):
        return b2a_hex(str(self))

o = octetstring('A')

print "o.__repr__():",o.__repr__()
print "o.__str__() :",o.__str__()
print "str(o)      :",str(o)
print "o           :",o

The result is pretty strange:

o.__repr__(): 41
o.__str__() : 41
str(o)      : A
o           : A

I'm not shure what's the exact reason for this problem. Either __str__
isn't used for str() and print.  Or I'm trapped in an chicken egg problem:
I have to convert self to an string (otherwise b2a_hex won't work) to do
this Python should use __str__ (which is the method I'm changing).

cu andreas

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