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Date: Sat, 22 Jun 2013 11:40:09 +1000
Subject: Re: Default Value
From: Chris Angelico <rosuav@gmail.com>
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Xref: csiph.com comp.lang.python:48898

On Sat, Jun 22, 2013 at 11:31 AM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> Thinking about this, I think that the only safe thing to do in Rickython
> 4000 is to prohibit putting mutable objects inside tuples. Putting a list
> or a dict inside a tuple is just a bug waiting to happen!

I think you're onto something here, but you really haven't gone far
enough. Mutable objects *anywhere* are a problem. The solution?
Abolish mutable objects. Strings (bytes and Unicode), integers,
decimals (floats are a problem to many people), tuples of the above,
and dictionaries mapping any of the above to any other of the above,
should be enough to do everything.

ChrisA