Bitwise/Binary operations in Python < 2.1

[Alex Martelli]

petro wrote:
        ...

>>>def extractPriorityAndFacility(single32bitQuantity):
>>>    priority = single32bitQuantity & 7
>>>    facility = (single32bitQuantity >> 3) & 0xFFFFFFF
>>Depending on the meaning of "top" ...   ^-- might need 4 here??
>>>    return priority, facility
>>Just a nit, but I suppose it could make a difference.
> 
>     3 gives the right answers:
>     
>     <22> is generated by postfix, and gives 6 (info) for priority, and 2
> (SMTP) for facility. <62> is generated by Leafnode, and gives 6 for
> priority, 7 (news) for facility.
> 
>     Thanks, that did the trick.
> 
>     Could one of you that to me? I don't really understand how that
> worked.

Operator >> shifts a number rightwards (looking at the number as
a string of bit), and operator & applies a "mask" (a bit-by-bit
AND).  Are you familiar with bit manipulations at all?


Alex