cpython/Modules/xxmodule.c

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/* Use this file as a template to start implementing a module that
   also declares objects types. All occurrences of 'Xxo' should be changed
   to something reasonable for your objects. After that, all other
   occurrences of 'xx' should be changed to something reasonable for your
   module. If your module is named foo your sourcefile should be named
   foomodule.c.
   
   You will probably want to delete all references to 'x_attr' and add
   your own types of attributes instead.  Maybe you want to name your
   local variables other than 'self'.  If your object type is needed in
   other files, you'll have to create a file "foobarobject.h"; see
   intobject.h for an example. */

/* Xxo objects */

#include "Python.h"

static PyObject *ErrorObject;

typedef struct {
	PyObject_HEAD
	PyObject	*x_attr;	/* Attributes dictionary */
} XxoObject;

staticforward PyTypeObject Xxo_Type;

#define XxoObject_Check(v)	((v)->ob_type == &Xxo_Type)

static XxoObject *
newXxoObject(arg)
	PyObject *arg;
{
	XxoObject *self;
	self = PyObject_NEW(XxoObject, &Xxo_Type);
	if (self == NULL)
		return NULL;
	self->x_attr = NULL;
	return self;
}

/* Xxo methods */

static void
Xxo_dealloc(self)
	XxoObject *self;
{
	Py_XDECREF(self->x_attr);
	PyMem_DEL(self);
}

static PyObject *
Xxo_demo(self, args)
	XxoObject *self;
	PyObject *args;
{
	if (!PyArg_ParseTuple(args, ""))
		return NULL;
	Py_INCREF(Py_None);
	return Py_None;
}

static PyMethodDef Xxo_methods[] = {
	{"demo",	(PyCFunction)Xxo_demo,	1},
	{NULL,		NULL}		/* sentinel */
};

static PyObject *
Xxo_getattr(self, name)
	XxoObject *self;
	char *name;
{
	if (self->x_attr != NULL) {
		PyObject *v = PyDict_GetItemString(self->x_attr, name);
		if (v != NULL) {
			Py_INCREF(v);
			return v;
		}
	}
	return Py_FindMethod(Xxo_methods, (PyObject *)self, name);
}

static int
Xxo_setattr(self, name, v)
	XxoObject *self;
	char *name;
	PyObject *v;
{
	if (self->x_attr == NULL) {
		self->x_attr = PyDict_New();
		if (self->x_attr == NULL)
			return -1;
	}
	if (v == NULL) {
		int rv = PyDict_DelItemString(self->x_attr, name);
		if (rv < 0)
			PyErr_SetString(PyExc_AttributeError,
			        "delete non-existing Xxo attribute");
		return rv;
	}
	else
		return PyDict_SetItemString(self->x_attr, name, v);
}

staticforward PyTypeObject Xxo_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,			/*ob_size*/
	"Xxo",			/*tp_name*/
	sizeof(XxoObject),	/*tp_basicsize*/
	0,			/*tp_itemsize*/
	/* methods */
	(destructor)Xxo_dealloc, /*tp_dealloc*/
	0,			/*tp_print*/
	(getattrfunc)Xxo_getattr, /*tp_getattr*/
	(setattrfunc)Xxo_setattr, /*tp_setattr*/
	0,			/*tp_compare*/
	0,			/*tp_repr*/
	0,			/*tp_as_number*/
	0,			/*tp_as_sequence*/
	0,			/*tp_as_mapping*/
	0,			/*tp_hash*/
};
/* --------------------------------------------------------------------- */

/* Function of two integers returning integer */

static PyObject *
xx_foo(self, args)
	PyObject *self; /* Not used */
	PyObject *args;
{
	long i, j;
	long res;
	if (!PyArg_ParseTuple(args, "ll", &i, &j))
		return NULL;
	res = i+j; /* XXX Do something here */
	return PyInt_FromLong(res);
}


/* Function of no arguments returning new Xxo object */

static PyObject *
xx_new(self, args)
	PyObject *self; /* Not used */
	PyObject *args;
{
	XxoObject *rv;
	
	if (!PyArg_ParseTuple(args, ""))
		return NULL;
	rv = newXxoObject(args);
	if ( rv == NULL )
	    return NULL;
	return (PyObject *)rv;
}

/* Example with subtle bug from extensions manual ("Thin Ice"). */

static PyObject *
xx_bug(self, args)
    PyObject *self;
    PyObject *args;
{
	PyObject *list, *item;
	
	if (!PyArg_ParseTuple(args, "O", &list))
		return NULL;
	
	item = PyList_GetItem(list, 0);
	/* Py_INCREF(item); */
	PyList_SetItem(list, 1, PyInt_FromLong(0L));
	PyObject_Print(item, stdout, 0);
	printf("\n");
	/* Py_DECREF(item); */
	
	Py_INCREF(Py_None);
	return Py_None;
}


/* List of functions defined in the module */

static PyMethodDef xx_methods[] = {
	{"foo",		xx_foo,		1},
	{"new",		xx_new,		1},
	{"bug",		xx_bug,		1},
	{NULL,		NULL}		/* sentinel */
};


/* Initialization function for the module (*must* be called initxx) */

void
initxx()
{
	PyObject *m, *d;

	/* Create the module and add the functions */
	m = Py_InitModule("xx", xx_methods);

	/* Add some symbolic constants to the module */
	d = PyModule_GetDict(m);
	ErrorObject = PyString_FromString("xx.error");
	PyDict_SetItemString(d, "error", ErrorObject);

	/* Check for errors */
	if (PyErr_Occurred())
		Py_FatalError("can't initialize module xx");
}