The __new__ method is where you should perform basic C-level initialisation of the object, including allocation of any C data structures that your object will own. You need to be careful what you do in the __new__ method, because the object may not yet be a valid Python object when it is called. Therefore, you must not invoke any Python operations which might touch the object; in particular, do not try to call any of its methods.
Unlike the corresponding method in Python, your __new__ method is not responsible for creating the object. By the time your __new__ method is called, memory has been allocated for the object and any C attributes it has have been initialised to 0 or null. (Any Python attributes have also been initialised to None, but you probably shouldn't rely on that.) Your __new__ method is guaranteed to be called exactly once.
Any initialisation which cannot safely be done in the __new__ method should be done in the __init__ method. By the time __init__ is called, the object is a fully valid Python object and all operations are safe. Under some circumstances it is possible for __init__ to be called more than once or not to be called at all, so your other methods should be designed to be robust under such situations.
You need to be careful what you do in a __dealloc__ method. By the time your __dealloc__ method is called, the object may already have been partially destroyed and may not be in a valid state as far as Python is concerned, so you should avoid invoking any Python operations which might touch the object. In particular, don't call any other methods of the object or do anything which might cause the object to be resurrected. It's best if you stick to just deallocating C data.
You don't need to worry about deallocating Python attributes of your object, because that will be done for you by Pyrex after your __dealloc__ method returns.
This means that you can't rely on the first parameter of these methods being "self", and you should test the types of both operands before deciding what to do. If you can't handle the combination of types you've been given, you should return NotImplemented.
This also applies to the in-place arithmetic method __ipow__. It doesn't apply to any of the other in-place methods (__iadd__, etc.) which always take self as the first argument.
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You don't have to declare your method as taking these parameter types.
If you declare different types, conversions will be performed as necessary.
| Name | Parameters | Return type | Description |
| General | |||
| __new__ | self, ... | Basic initialisation (no direct Python equivalent) | |
| __init__ | self, ... | Further initialisation | |
| __dealloc__ | self | Basic deallocation (no direct Python equivalent) | |
| __cmp__ | x, y | int | 3-way comparison |
| __richcmp__ | x, y, int op | object | Rich comparison (no direct Python equivalent) |
| __str__ | self | object | str(self) |
| __repr__ | self | object | repr(self) |
| __hash__ | self | int | Hash function |
| __call__ | self, ... | object | self(...) |
| __iter__ | self | object | Return iterator for sequence |
| __getattr__ | self, name | object | Get attribute |
| __setattr__ | self, name, val | Set attribute | |
| __delattr__ | self, name | Delete attribute | |
| Arithmetic operators | |||
| __add__ | x, y | object | binary + operator |
| __sub__ | x, y | object | binary - operator |
| __mul__ | x, y | object | * operator |
| __div__ | x, y | object | / operator for old-style division |
| __floordiv__ | x, y | object | // operator |
| __truediv__ | x, y | object | / operator for new-style division |
| __mod__ | x, y | object | % operator |
| __divmod__ | x, y | object | combined div and mod |
| __pow__ | x, y, z | object | ** operator or pow(x, y, z) |
| __neg__ | self | object | unary - operator |
| __pos__ | self | object | unary + operator |
| __abs__ | self | object | absolute value |
| __nonzero__ | self | int | convert to boolean |
| __invert__ | self | object | ~ operator |
| __lshift__ | x, y | object | << operator |
| __rshift__ | x, y | object | >> operator |
| __and__ | x, y | object | & operator |
| __or__ | x, y | object | | operator |
| __xor__ | x, y | object | ^ operator |
| Numeric conversions | |||
| __int__ | self | object | Convert to integer |
| __long__ | self | object | Convert to long integer |
| __float__ | self | object | Convert to float |
| __oct__ | self | object | Convert to octal |
| __hex__ | self | object | Convert to hexadecimal |
| In-place arithmetic operators | |||
| __iadd__ | self, x | object | += operator |
| __isub__ | self, x | object | -= operator |
| __imul__ | self, x | object | *= operator |
| __idiv__ | self, x | object | /= operator for old-style division |
| __ifloordiv__ | self, x | object | //= operator |
| __itruediv__ | self, x | object | /= operator for new-style division |
| __imod__ | self, x | object | %= operator |
| __ipow__ | x, y, z | object | **= operator |
| __ilshift__ | self, x | object | <<= operator |
| __irshift__ | self, x | object | >>= operator |
| __iand__ | self, x | object | &= operator |
| __ior__ | self, x | object | |= operator |
| __ixor__ | self, x | object | ^= operator |
| Sequences and mappings | |||
| __len__ | self | int | len(self) |
| __getitem__ | self, x | object | self[x] |
| __setitem__ | self, x, y | self[x] = y | |
| __delitem__ | self, x | del self[x] | |
| __getslice__ | self, int i, int j | object | self[i:j] |
| __setslice__ | self, int i, int j, x | self[i:j] = x | |
| __delslice__ | self, int i, int j | del self[i:j] | |
| __contains__ | self, x | int | x in self |
| Iterators | |||
| __next__ | self | object | Get next item (called next in Python) |
| Buffer interface (no Python equivalents) | |||
| __getreadbuffer__ | self, int i, void **p | ||
| __getwritebuffer__ | self, int i, void **p | ||
| __getsegcount__ | self, int *p | ||
| __getcharbuffer__ | self, int i, char **p | ||
| Descriptor objects (no Python equivalents) | |||
| __get__ | self, x, y | object | |
| __set__ | self, x, y | object | |