Awkwardness of C API for making tuples

[Dave Opstad]

In article <1107289261.185768.116790 at f14g2000cwb.googlegroups.com>,
 "John Machin" <sjmachin at lexicon.net> wrote:

> What is the purpose of this first loop?

Error handling. If I can't successfully create all the PyInts then I can 
dispose the ones I've made and not bother making the tuple at all.
> 
> In what variable-length storage are you storing these (Python) integers
> during this first loop? Something you created with (a) PyMem_Malloc (b)
> malloc (c) alloca (d) your_own_malloc?

(b) malloc. The sequence here is: 1) malloc; 2) check for malloc 
success; 3) loop to create PyInts (if failure, Py_DECREF those made so 
far and free the malloc'ed buffer); 4) create new tuple (error checks 
again); and 5) PyTuple_SET_ITEM (no error checks needed)

> 1. Determine the length of the required tuple; this may need a loop,
> but only to _count_ the number of C longs that you have.
> 2. Use PyTuple_New.
> 3. Loop to fill the tuple, using PyInt_FromLong and PyTuple_SetItem.

This would certainly be simpler, although I'm not sure I'm as clear as 
to what happens if, say, in the middle of this loop a PyInt_FromLong 
fails. I know that PyTuple_SetItem steals the reference; does that mean 
I could just Py_DECREF the tuple and all the pieces will be 
automagically freed? If so, I'll take your recommendation and rework the 
logic this way.

Thanks!
Dave