(original) (raw)

From: Brett Cannon \[mailto:brett@python.org\]
Sent: Friday, January 15, 2016 6:58 PM
To: Eddy Quicksall; python-dev@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.

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
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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