[Python-Dev] C struct for Str( )

[Eddy Quicksall]

Sorry, I must be on the wrong list. Can you please give me the correct list?

 

Eddy

 

From: Brett Cannon [mailto:brett at python.org] 
Sent: Friday, January 15, 2016 6:58 PM
To: Eddy Quicksall; python-dev at python.org
Subject: Re: [Python-Dev] C struct for Str( )

 

I don't quite see what this has to do with has to do with the development of Python, Eddy. You can always reference the C API at https://docs.python.org/3/c-api/index.html . And `PyBytesObject` is an instance of `bytes` in Python.

 

On Fri, 15 Jan 2016 at 15:33 Eddy Quicksall <Eddy at quicksall.com> wrote:

I want to fill an Str() string from a C function. But I think I am using the
wrong structure (PyBytesObject). I have written a C function to dump the
Python class but as you can see the structure I'm using does not match the
data in the class.

Can someone please tell me the correct structure:

--------- Python snip ---------
class _vendorRecord_2:
    vendorListNumber        = str()
    vendorNumber            = str()
    vendorName              = str('x' * 20)

vendorRecord_2 = _vendorRecord_2()

print(len(vendorRecord_2.vendorName))
print(vendorRecord_2.vendorName + '|')
XBaseDump_PythonString(py_object(vendorRecord_2.vendorName))

--------- C function --------
#define MS_NO_COREDLL
#undef _DEBUG
#include <W:\Python-3.5.1\Include\python.h>
DSI_DLL void CALL_TYPE XBaseDump_PythonString( PyBytesObject *pBytesObject )
{
    printf( "ob_size = %d, ob_shash = %X, ob_sval = %s\n",
pBytesObject->ob_base.ob_size, pBytesObject->ob_shash, pBytesObject->ob_sval
);
    printf( "offsetof(ob_size) = %d, offsetof(ob_sval) = %d\n", offsetof(
PyBytesObject, ob_base.ob_size ),
        offsetof( PyBytesObject, ob_sval ) );
    printf( "sizeof(PyBytesObject) = %d\n", sizeof(PyBytesObject) );
    DsmDumpBytes( pBytesObject, 32 );
}

-------- output ------------
20
xxxxxxxxxxxxxxxxxxxx|
ob_size = 20, ob_shash = 70768D53, ob_sval = σsci
offsetof(ob_size) = 8, offsetof(ob_sval) = 16
sizeof(PyBytesObject) = 20
0000: 03 00 00 00 60 B0 DC 1D 14 00 00 00 53 8D 76 70 ....-...........
0016: E5 73 63 69 00 00 00 00 78 78 78 78 78 78 78 78 V...............




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