[Python-Dev] python 3.0, tp_compare not used for == test? (original) (raw)

Campbell Barton ideasman42 at gmail.com
Mon Feb 2 06:12:37 CET 2009

Hi, I have been writing a new C api that can build with both python 2.6 and 3.0

I found that when building with python 2.6, doing "a==b" between 2 different pyrna_struct_Type's would run tp_compare

But with python 3.0, "a==b" will always be false and tp_compare function would not even run. The only way to get it to run the tp_compare function was to do "cmp(a, b)" however Id like to be able to use == still.

The only way I could get "a==b" to work in python 3.0 was to add a tp_richcompare function which runs tp_compare with Py_CmpToRich() anyway

Is this the intended behavior? - if so its important for external C API's to be updated to support this.

Included the PyType below with some relevant details. I looked at other Python 3.0 types but could not see why this would happen.

// ----snip, // initialized with PyType_Ready

if( PyType_Ready( &pyrna_struct_Type ) < 0 )
    return NULL;

// header definition for BPy_StructRNA

typedef struct { PyObject_HEAD /* required python macro / PointerRNA ptr; int freeptr; / needed in some cases if ptr.data is created on the fly, free when deallocing */ } BPy_StructRNA;

// PyType

/-----------------------BPy_StructRNA method def------------------------------/ PyTypeObject pyrna_struct_Type = { PyVarObject_HEAD_INIT(NULL, 0) "StructRNA", /* tp_name / sizeof( BPy_StructRNA ), / tp_basicsize / 0, / tp_itemsize / / methods / ( destructor ) pyrna_struct_dealloc,/ tp_dealloc / NULL, / printfunc tp_print; / NULL, / getattrfunc tp_getattr; / NULL, / setattrfunc tp_setattr; / ( cmpfunc ) pyrna_struct_compare, / tp_compare / ( reprfunc ) pyrna_struct_repr, / tp_repr */

/* Method suites for standard classes */

NULL,                       /* PyNumberMethods *tp_as_number; */
NULL,						/* PySequenceMethods *tp_as_sequence; */
NULL,						/* PyMappingMethods *tp_as_mapping; */

/* More standard operations (here for binary compatibility) */

( hashfunc )pyrna_struct_hash,	/* hashfunc tp_hash; */
NULL,						/* ternaryfunc tp_call; */
NULL,                       /* reprfunc tp_str; */
( getattrofunc ) pyrna_struct_getattro,	/* getattrofunc tp_getattro; */
( setattrofunc ) pyrna_struct_setattro,	/* setattrofunc tp_setattro; */

/* Functions to access object as input/output buffer */
NULL,                       /* PyBufferProcs *tp_as_buffer; */

/*** Flags to define presence of optional/expanded features ***/ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* long tp_flags; */

NULL,						/*  char *tp_doc;  Documentation string */

/*** Assigned meaning in release 2.0 ***/ /* call function for all accessible objects / NULL, / traverseproc tp_traverse; */

/* delete references to contained objects */
NULL,                       /* inquiry tp_clear; */

/*** Assigned meaning in release 2.1 / / rich comparisons ***/ (richcmpfunc)pyrna_struct_richcmp, /* richcmpfunc tp_richcompare; */

/*** weak reference enabler ***/ 0, /* long tp_weaklistoffset; */

/*** Added in release 2.2 ***/ /* Iterators / NULL, / getiterfunc tp_iter; / NULL, / iternextfunc tp_iternext; */

/*** Attribute descriptor and subclassing stuff ***/ pyrna_struct_methods, /* struct PyMethodDef *tp_methods; / NULL, / struct PyMemberDef *tp_members; / NULL, / struct PyGetSetDef *tp_getset; / NULL, / struct _typeobject *tp_base; / NULL, / PyObject *tp_dict; / NULL, / descrgetfunc tp_descr_get; / NULL, / descrsetfunc tp_descr_set; / 0, / long tp_dictoffset; / NULL, / initproc tp_init; / NULL, / allocfunc tp_alloc; / pyrna_struct_new, / newfunc tp_new; / / Low-level free-memory routine / NULL, / freefunc tp_free; / / For PyObject_IS_GC / NULL, / inquiry tp_is_gc; / NULL, / PyObject *tp_bases; / / method resolution order / NULL, / PyObject *tp_mro; / NULL, / PyObject *tp_cache; / NULL, / PyObject *tp_subclasses; / NULL, / PyObject *tp_weaklist; */ NULL };

--

More information about the Python-Dev mailing list