[Python-Dev] C struct for Str( ) (original) (raw)

Brett Cannon brett at python.org
Fri Jan 15 18:58:07 EST 2016

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 vendorRecord2: vendorListNumber = str() vendorNumber = str() vendorName = str('x' * 20) vendorRecord2 = vendorRecord2() print(len(vendorRecord2.vendorName)) print(vendorRecord2.vendorName + '|') XBaseDumpPythonString(pyobject(vendorRecord2.vendorName)) --------- C function -------- #define MSNOCOREDLL #undef DEBUG #include <W:\Python-3.5.1\Include\python.h> DSIDLL void CALLTYPE XBaseDumpPythonString( PyBytesObject *pBytesObject ) { printf( "obsize = %d, obshash = %X, obsval = %s\n", pBytesObject->obbase.obsize, pBytesObject->obshash, pBytesObject->obsval ); printf( "offsetof(obsize) = %d, offsetof(obsval) = %d\n", offsetof( PyBytesObject, obbase.obsize ), offsetof( PyBytesObject, obsval ) ); printf( "sizeof(PyBytesObject) = %d\n", sizeof(PyBytesObject) ); DsmDumpBytes( pBytesObject, 32 ); } -------- output ------------ 20 xxxxxxxxxxxxxxxxxxxx| obsize = 20, obshash = 70768D53, obsval = σsci offsetof(obsize) = 8, offsetof(obsval) = 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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