Re: [PyKDE] Sip support for FILE */PyFileObject

2005-10-11 Thread Phil Thompson 
 Hello all,

 We'd like to be able to mix C++ and Python for reading
 and writing of heavy-weight streams of data.  Although
 QFile can be used across both C++ and Python using PyQt,
 it is somewhat more appealing to use native python files
 in Python and native FILE * in C/C++.

 We've come up with a working solution to convert
 a PyFileObject to a FILE * using sip:

  MyWriter(SIP_PYOBJECT);
 %MethodCode
  if (PyFile_Check(a0))
  sipCpp = new MyWriter(PyFile_AsFile(a0));
  else
  {
  sipCpp = NULL;
  sipIsErr = 1;
  PyErr_SetNone(PyExc_TypeError);
  }
 %End

 We can think of two other variations that would
 require changes to sip, but would reduce the need
 for method code...

 (a)

  MyWriter(SIP_PYFILE);
 %MethodCode
  sipCpp = new MyWriter(PyFile_AsFile(a0));
 %End

 (b)

  MyWriter(FILE *);

 Another thing we've tried is creating a binding
 for struct FILE, but the sip-generated code
 is inclined to delete it once passed to
 MyWriter...

 struct FILE
 {
 %TypeHeaderCode
 #include cstdio
 using namespace std;
 %End

 private:
  FILE();
  FILE(const FILE );
  ~FILE();

 %ConvertToTypeCode

  if (sipIsErr == NULL)
  return PyFile_Check(sipPy);

  if (PyFile_Check(sipPy))
  {
 *sipCppPtr = PyFile_AsFile(sipPy);
 return 1;
  }

  *sipIsErr = 1;
  return 0;
 %End
 };

 Any hints or suggestions appreciated.

I don't know what you mean by inclined to delete it. It should follow
the normal garbage collection rules. If you want MyWriter to take
ownership of the FILE then take ownership of it in the ctor.

As file is a C structure I would also wrap it in a %CModule rather than a
C++ %Module.

Phil

___
PyKDE mailing listPyKDE@mats.imk.fraunhofer.de
http://mats.imk.fraunhofer.de/mailman/listinfo/pykde

Re: [PyKDE] Sip support for FILE */PyFileObject

2005-10-11 Thread Nigel Stewart 

There seems to be an assumption that %ConvertToTypeCode creates
a copy that needs to be deleted and ownership can't be transferred
to C++.


It's not an assumption - it's the return value of %ConvertToTypeCode. Just 
make sure it always returns 0.


Yes, that is the solution to the problem.
Many thanks!

Nigel



From the Sip documentation...

If sipIsErr is not NULL then a non-zero value is returned if the mapped
 type instance returned through sipCppPtr was created on the heap.
 Otherwise zero is returned.



struct FILE
{
%TypeHeaderCode
#include cstdio
using namespace std;
%End

private:
FILE();
FILE(const FILE );
~FILE();

%ConvertToTypeCode
if (sipIsErr == NULL)
return PyFile_Check(sipPy);

if (PyFile_Check(sipPy))
{
   *sipCppPtr = PyFile_AsFile(sipPy);
   return 0;  /* The item was not allocated on the heap */
}

*sipIsErr = 1;
return 0;
%End
};

___
PyKDE mailing listPyKDE@mats.imk.fraunhofer.de
http://mats.imk.fraunhofer.de/mailman/listinfo/pykde

[PyKDE] Sip support for FILE */PyFileObject

2005-10-10 Thread Nigel Stewart 

Hello all,

We'd like to be able to mix C++ and Python for reading
and writing of heavy-weight streams of data.  Although
QFile can be used across both C++ and Python using PyQt,
it is somewhat more appealing to use native python files
in Python and native FILE * in C/C++.

We've come up with a working solution to convert
a PyFileObject to a FILE * using sip:

MyWriter(SIP_PYOBJECT);
%MethodCode
if (PyFile_Check(a0))
sipCpp = new MyWriter(PyFile_AsFile(a0));
else
{
sipCpp = NULL;
sipIsErr = 1;
PyErr_SetNone(PyExc_TypeError);
}
%End

We can think of two other variations that would
require changes to sip, but would reduce the need
for method code...

(a)

MyWriter(SIP_PYFILE);
%MethodCode
sipCpp = new MyWriter(PyFile_AsFile(a0));
%End

(b)

MyWriter(FILE *);

Another thing we've tried is creating a binding
for struct FILE, but the sip-generated code
is inclined to delete it once passed to
MyWriter...

struct FILE
{
%TypeHeaderCode
#include cstdio
using namespace std;
%End

private:
FILE();
FILE(const FILE );
~FILE();

%ConvertToTypeCode

if (sipIsErr == NULL)
return PyFile_Check(sipPy);

if (PyFile_Check(sipPy))
{
   *sipCppPtr = PyFile_AsFile(sipPy);
   return 1;
}

*sipIsErr = 1;
return 0;
%End
};

Any hints or suggestions appreciated.

Regards,

Nigel Stewart

___
PyKDE mailing listPyKDE@mats.imk.fraunhofer.de
http://mats.imk.fraunhofer.de/mailman/listinfo/pykde