Is it possible to change the default __add__ method to do something else than just add?
For example, if the goal is with this line:
5+5 get The answer is 10 or anything else like 0 by changing __add__ to be x-y instead of x+y?
I know I can change __add__ in my own classes:
class Vec():
def __init__(self,x,y):
self.x = x
self.y = y
def __repr__(self):
return f'{self.x, self.y}'
def __add__(self, other):
self.x += other.x
self.y += other.y
return Vec(self.x,self.y)
v1 = Vec(1,2)
v2 = Vec(5,3)
v1+v2
# (6, 5)
Can I somehow target the default __add__ method to change its behaviour? I intuitively think that __add__ is defined in each default data type to return specific results, but then again, the __add__ method is what we address when changing it for a specific class, so, is it possible to change the main __add__ logic?
Something along these lines?
class __add__():
...
If you are looking for information about how the C level built-ins are defined you would want to look at some of the source code, note that I'm linking specifically to floats but the structure exists for all number types:
static PyNumberMethods float_as_number = {
float_add, /* nb_add */
float_sub, /* nb_subtract */
float_mul, /* nb_multiply */
this is the structure for all the C function pointers that implement number methods, (for floats in this case) each builtin type that defines any number related methods will define a PyNumberMethods structure, this is then used in the formal definition of the type:
PyTypeObject PyFloat_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"float",
sizeof(PyFloatObject),
...
&float_as_number, /* tp_as_number */
the PyTypeObject represents all the relevant information needed to construct the float object in python, (or equivalently, int or str etc.) containing all the methods, attributes, and necessary meta-data to work as a python type. So if you really wanted to change adding floats to instead do another well defined task you'd just change it to point to the other function:
static PyNumberMethods float_as_number = {
float_sub, /* nb_add. overrides to do subtraction because I want to break everything >:D */
float_sub, /* nb_subtract */
If you wanted to write your own behaviour you could write your own function and point to it in this structure instead.