is None or == None ?

[Vincent Manis]

On 2009-11-10, at 22:07, Vincent Manis wrote:

> On 2009-11-10, at 19:07, Steven D'Aprano wrote:
>> In fact, in Inside Mac Vol II, Apple explicitly gives the format of 
>> pointers: the low-order three bytes are the address, the high-order byte 
>> is used for flags: bit 7 was the lock bit, bit 6 the purge bit and bit 5 
>> the resource bit. The other five bits were unused.

I inadvertently must have deleted a paragraph in the response I just posted. Please add: The pointer format would have caused me to write macros or the like (that was still in the days when Apple liked Pascal) to hide the bit representation of pointers. 

-- v