[Python-Dev] PEP: Adding data-type objects to Python

[Alexander Belopolsky]

Travis E. Oliphant <oliphant.travis <at> ieee.org> writes:

> 
> Alexander Belopolsky wrote:
> > ...
> > 1. Should primitive types be associated with simple type codes
 (short, 
int, long,
> > float, double) or type/size pairs [(int,16), (int, 32), (int, 64), 
(float, 32), 
> > (float, 64)]?
> >      - I prefer pairs
> > 
> > 2. Should primitive type codes be characters or integers (from an 
enum) at
> > C level?
> >     - I prefer integers
> 
> Are these orthogonal?
> 

Do you mean are my quiestions 1 and 2 orthogonal? I guess they are.

> > 
> > 3. Should size be expressed in bits or bytes?
> >     - I prefer bits
> > 
> 
> So, you want an integer enum for the "kind" and an integer for the 
> bitsize?   That's fine with me.
> 
> One thing I just remembered.  We have T_UBYTE and T_BYTE, etc. defined 
> in structmember.h already.  Should we just re-use those #defines while 
> adding to them to make an easy to use interface for primitive types?
> 

I was thinking about using something like NPY_TYPES enum, but T_* 
codes would work as well.  Let me just present both options for the
 record:

 --- numpy/ndarrayobject.h ---

enum NPY_TYPES {    NPY_BOOL=0,
                    NPY_BYTE, NPY_UBYTE,
                    NPY_SHORT, NPY_USHORT,
                    NPY_INT, NPY_UINT,
                    NPY_LONG, NPY_ULONG,
                    NPY_LONGLONG, NPY_ULONGLONG,
                    NPY_FLOAT, NPY_DOUBLE, NPY_LONGDOUBLE,
                    NPY_CFLOAT, NPY_CDOUBLE, NPY_CLONGDOUBLE,
                    NPY_OBJECT=17,
                    NPY_STRING, NPY_UNICODE,
                    NPY_VOID,
                    NPY_NTYPES,
                    NPY_NOTYPE,
                    NPY_CHAR,      /* special flag */
                    NPY_USERDEF=256  /* leave room for characters */
};

--- structmember.h ---

/* Types */
#define T_SHORT         0
#define T_INT           1
#define T_LONG          2
#define T_FLOAT         3
#define T_DOUBLE        4
#define T_STRING        5
#define T_OBJECT        6
/* XXX the ordering here is weird for binary compatibility */
#define T_CHAR          7       /* 1-character string */
#define T_BYTE          8       /* 8-bit signed int */
/* unsigned variants: */
#define T_UBYTE         9
#define T_USHORT        10
#define T_UINT          11
#define T_ULONG         12

/* Added by Jack: strings contained in the structure */
#define T_STRING_INPLACE        13

#define T_OBJECT_EX     16      /* Like T_OBJECT, but raises AttributeError
                                   when the value is NULL, instead of
                                   converting to None. */
#ifdef HAVE_LONG_LONG
#define T_LONGLONG      17  
#define T_ULONGLONG      18
#endif /* HAVE_LONG_LONG */