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Sun Mar 22 18:38:54 CET 2009 · https://mail.python.org/pipermail/python-dev/2009-March/087396.html

Christian Tismer wrote:
> ... but I'm curious.
>
> Hi Guido,
>
> while working on Psyco, I stumbled over a log entry in modsupport.h:
>
>>
>>    19-Aug-2002  GvR    1012    Changes to string object struct for
>>                    interning changes, saving 3 bytes.
>>
>
> The change to stringobject was this  (rev. 28308):
>
> Before:
>> typedef struct {
>>     PyObject_VAR_HEAD
>>     long ob_shash;
>>     PyObject *ob_sinterned;
>>     char ob_sval[1];
>> } PyStringObject;
>
> After:
>> typedef struct {
>>     PyObject_VAR_HEAD
>>     long ob_shash;
>>     int ob_sstate;
>>     char ob_sval[1];
>> } PyStringObject;
>
> Now, the internals are very clear to me. What I don't understand
> is where the three saved bytes should be.
>
> Thinking of the time where this change was made, I cannot imagine
> that this comment was about the size diff between pointer and int,
> and if this was meant, I still don't get how this could save three
> bytes?
>
> With unaligned ob_sval, structure packing and ob_sstate being
> unsigned char one could save 3 bytes, but we don't do that.
>
> Well, as said, this is no important question. I am just asking
> myself what I don't see here, or if the comment is just sub-optimal :-)
>

At Resolver we've found it useful to short-circuit any doubt and just 
refer to comments in code as 'lies'. :-)

Michael

> all the best -- chris
>
>
> p.s.: won't make it to PyCon this time, see you soon at the piggies

-- 
http://www.ironpythoninaction.com/
http://www.voidspace.org.uk/blog

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[Python-Dev] an unimportant question, ...