strtok and return value of PyString_AsString()

[Les Schaffer]

i am finishing up a C extension in which i feed a list of strings (a
long list), and do a strtok on each item of the list.

i use PyString_AsString() to grab a char * pointer to the "string".

i then do a strtok(pointer ...), strtok(NULL, ...), etc etc

in the docs for Python/C API, it says for PyString_AsString :

   Returns a null-terminated representation of the contents of
   string. The pointer refers to the internal buffer of string, not a
   copy. The data must not be modified in any way. It must not be
   de-allocated.

the question is, why am i getting away with murder? i thought strtok
ate its first argument for breakfast? i checked the strings in the
list back in python after the call to extension function, and the
strings were intact. so i am confused.

[i was previously using strdup to copy the string (as per glibc docs),
but didnt like all the (implied) malloc's and explicit free()'s i
needed.]

only thing i can think of is that PyString_AsString __is__ malloc'ing
some memoery and passing a copy of strobject's data on each call. but
then there's the malloc/free i was trying to avoid.

thanks for any insight.

les schaffer

p.s. i don't understand stringobject.h definition of a string object:

typedef struct {
        PyObject_VAR_HEAD
#ifdef CACHE_HASH
        long ob_shash;
#endif
#ifdef INTERN_STRINGS
        PyObject *ob_sinterned;
#endif
        char ob_sval[1];
} PyStringObject;


why is ob_sval only one character long? where's da string????

guesstomate: ob_sval is the first letter of the string, which is
interned (whatever that means ;-) and when you go to grab the string,
its looked up in some tree somewhere starting with the first
letter?????

or sumpin like that?????????????

but then how does this return a string if ob_sval is a 1 element
character array? :

    #define PyString_AS_STRING(op) (((PyStringObject *)(op))->ob_sval)



signed 'dazed and confused'