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Date: Thu, 2 Oct 2014 23:27:37 +1000
Subject: Re: Assignment Operators?
From: Chris Angelico <rosuav@gmail.com>
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Xref: csiph.com comp.lang.python:78601

On Thu, Oct 2, 2014 at 11:24 PM, Didymus <lynto28@gmail.com> wrote:
>>>> errors = False
>>>> errors |= 3
>>>> errors
> 3
>>>> errors |= 4
>>>> errors
> 7
>
>    The '|=' operator, I read should be like a = a | b, but this appears to add the two numbers as long as it's more than the previous:
>
>>>> errors |= 5
>>>> errors
> 7

It is indeed (mostly) equivalent to "a = a | b". Do you understand
what bitwise 'or' does?

When you use False there, it's equivalent to zero. Everything after
that is straight-forward bitwise or.

http://en.wikipedia.org/wiki/Bitwise_operation#OR

ChrisA