join vs instances

Michael Hudson mwh at
Mon Dec 10 12:56:03 CET 2001

Robin Becker <robin at> writes:

> what do I need in a class to get an instance to respect the string
> join?

Unfortunately, you can't.

There is no satisfactory distinction on when things like this work and
when they don't, but there's a general movement in favour of being
more flexible, i.e. ''.join(UserString('ab')) might work at some
point.  Doesn't seem to in 2.2b2+, though.

As a work around, it you control the call of string.join, replace



    sep.join(map(str, seq))


  Good? Bad? Strap him into the IETF-approved witch-dunking
  apparatus immediately!                        -- NTK now, 21/07/2000

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