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

Christian Tismer tismer at stackless.com
Sun Mar 22 17:38:37 CET 2009

... 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):

> typedef struct {
>     PyObject_VAR_HEAD
>     long ob_shash;
>     PyObject *ob_sinterned;
>     char ob_sval[1];
> } PyStringObject;

> 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

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 :-)

all the best -- chris

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