Python type createion

Now I'm looking at Python3.0 source code.

PyTypeObject PyUnicode_Type = {
 PyVarObject_HEAD_INIT(&PyType_Type, 0)
 "str",              /* tp_name */
 sizeof(PyUnicodeObject),        /* tp_size */
 ...(snip)...
 &unicode_as_number,         /* tp_as_number */
 &unicode_as_sequence,       /* tp_as_sequence */
 &unicode_as_mapping,        /* tp_as_mapping */
 (hashfunc) unicode_hash,        /* tp_hash*/
 0,                  /* tp_call*/
 (reprfunc) unicode_str,     /* tp_str */
 ...(snip)...

This is a code snippet from Python3.01 unicode object implementation. tp_as_sequence is a behavior definition when the object is used as a sequence, tp_as_mapping is a behavior when used as a mapping object. unicode_as_sequence is defined like this.

static PySequenceMethods unicode_as_sequence = {
 (lenfunc) unicode_length,       /* sq_length */
 PyUnicode_Concat,           /* sq_concat */
 (ssizeargfunc) unicode_repeat,  /* sq_repeat */
 (ssizeargfunc) unicode_getitem,     /* sq_item */
 0,                  /* sq_slice */
 0,                  /* sq_ass_item */
 0,                  /* sq_ass_slice */
 PyUnicode_Contains,         /* sq_contains */
};

unicode_repeat etc. are just a simple C function.

Another code snippet taken from bool object implementation. bool is a subtype of int. It is specified by setting PyLong_Type(i.e. int) to tp_base entry.

PyTypeObject PyBool_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"bool",
     ...(snip)...
&PyLong_Type,    /* tp_base */
     ...(snip)...
};

Simple enough.


(Above code snippets are Python licensed)