ó ¿œ^c@s<dZddd„ƒYZd„Zedkr8eƒndS(sð A class which presents the reverse of a sequence without duplicating it. From: "Steven D. Majewski" It works on mutable or inmutable sequences. >>> chars = list(Rev('Hello World!')) >>> print ''.join(chars) !dlroW olleH The .forw is so you can use anonymous sequences in __init__, and still keep a reference the forward sequence. ) If you give it a non-anonymous mutable sequence, the reverse sequence will track the updated values. ( but not reassignment! - another good reason to use anonymous values in creating the sequence to avoid confusion. Maybe it should be change to copy input sequence to break the connection completely ? ) >>> nnn = range(3) >>> rnn = Rev(nnn) >>> for n in rnn: print n ... 2 1 0 >>> for n in range(4, 6): nnn.append(n) # update nnn ... >>> for n in rnn: print n # prints reversed updated values ... 5 4 2 1 0 >>> nnn = nnn[1:-1] >>> nnn [1, 2, 4] >>> for n in rnn: print n # prints reversed values of old nnn ... 5 4 2 1 0 # >>> WH = Rev('Hello World!') >>> print WH.forw, WH.back Hello World! !dlroW olleH >>> nnn = Rev(range(1, 10)) >>> print nnn.forw [1, 2, 3, 4, 5, 6, 7, 8, 9] >>> print nnn.back [9, 8, 7, 6, 5, 4, 3, 2, 1] >>> rrr = Rev(nnn) >>> rrr <1, 2, 3, 4, 5, 6, 7, 8, 9> tRevcBs,eZd„Zd„Zd„Zd„ZRS(cCs||_||_dS(N(tforwtback(tselftseq((s(/usr/lib64/python2.7/Demo/classes/Rev.pyt__init__?s cCs t|jƒS(N(tlenR(R((s(/usr/lib64/python2.7/Demo/classes/Rev.pyt__len__CscCs|j|d S(Ni(R(Rtj((s(/usr/lib64/python2.7/Demo/classes/Rev.pyt __getitem__FscCs®|j}t|tƒr'd}d}nHt|tƒrEd}d}n*t|tƒrcd}d}n d}d}g|jD]}t|ƒ^qy}|d |j|ƒ|dS(Ns[]s, s()ts<>iiÿÿÿÿ(Rt isinstancetlistttupletstrRtjoin(RRtwraptseptitemtoutstrs((s(/usr/lib64/python2.7/Demo/classes/Rev.pyt__repr__Is    "(t__name__t __module__RRR R(((s(/usr/lib64/python2.7/Demo/classes/Rev.pyR>s   cCs%ddl}ddl}|j|ƒS(Niÿÿÿÿ(tdoctestRttestmod(RR((s(/usr/lib64/python2.7/Demo/classes/Rev.pyt_testZst__main__N((t__doc__RRR(((s(/usr/lib64/python2.7/Demo/classes/Rev.pyt<s