[Numpy-discussion] Wrapping C array

[Carlos Pita]

> > The documentation for PyArray_FromDimsAndData
> > that I quoted in my previous post seems to suggest
> > that a copy is done. But browsing the web
> 
> I'd appreciate it if you could send me a reference to where that is
> because it is stale.

I take the excerpt from the numarray user manual from
the python2.3-numarray 1.1.1 debian (sarge) package.
But it's updated in the cvs:

\begin{cfuncdesc}{PyObject*}{PyArray_FromDimsAndData}{int nd, int *dims, int type, char *data}
   This function will allocate a numarray of the specified shape and type
   which will refer to the data buffer specified by \var{data}.  The contents
   of \var{data} will not be copied nor will \var{data} be deallocated upon
   the deletion of the array.
\end{cfuncdesc}

It seems to be ok. When it says "nor will \var{data} be deallocated upon
the deletion of the array", does it mean that the python buffer object
ref count won't be decremented ? Or, more generally, the created
numarray will refer directly to the C array segments exposed by the
python buffer object or will keep a reference to this object?

> Not in my opinion, for two reasons:
> 
> 1.  PyArray_FromDimsAndData is easier to use,  internalizing the buffer
> creation step.
> 
> 2.  These days,  my recommendation is to use the Numeric compatibility
> layer because it gives the best portability,  to Numeric now and to

I will take your advice.

Thank you!
Regards,
Carlos