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18-special-methods.py
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18-special-methods.py
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# Special methods a.k.a dunder methods (double underscore)
# __init__
# __str__
# __repr__
class ABC:
# This functions runs automatiacly while creating an instance/object from the class
# This is mainly used for setting variable or doing some initialization
def __init__(self):
# print("__init__")
self.name = "Lets Code Together"
def run(self):
print("RUN")
# Not formal
# We mainly write what teh class is suppose to do
def __str__(self):
return "Instance of class ABC"
# Formal
# This is mainly used for debugger
def __repr__(self):
return "ABC()"
# abc = ABC()
# # abc.run()
# print(abc)
# Doing Arithemetic
# __add__
# __sub__
# __mul__
# real + imaginary
# x = a + ib
# y = c + id
# x + y
# (a+c) + i(b+d)
class ComplexNumber:
def __init__(self, real, imag):
self.real = real
self.imag = imag
def __add__(self, other):
# print(vars(self)) # This print all the variable in the object
# print(vars(other))
real = self.real + other.real
imag = self.imag + other.imag
return ComplexNumber(real, imag)
def __sub__(self, other):
real = self.real - other.real
imag = self.imag - other.imag
return ComplexNumber(real, imag)
cmplx1 = ComplexNumber(10, 5)
cmplx2 = ComplexNumber(20, 10)
cmplx3 = ComplexNumber(30, 15)
# self + other = self + other
# result = cmplx1 + cmplx2 + cmplx3
result = cmplx1 - cmplx2
# print(result)
print(f"{result.real} + {result.imag}i")
# x = [1, 2, 3, 4, 5]
# print(len(x))
# __len__
class MyList:
def __init__(self):
self.words = []
def add(self, word):
self.words.append(word)
def __len__(self):
return len(self.words)
list1 = MyList()
list1.add("Hello")
list1.add("There")
list1.add("!")
print(list1)
print(len(list1.words))
print(len(list1))
for i in range(10):
print(i)
# __iter__
# __next__
class MyRange:
def __init__(self, start, end):
self.start = start
self.end = end
def __iter__(self):
return self
def __next__(self):
if self.start < self.end:
self.start += 1
return self.start - 1
else:
raise StopIteration
range1 = MyRange(0, 10)
for i in range1:
print(i)
# __getitem__
# __setitem__
dict1 = {"1": "One"}
print(dict1["1"]) # this is using getitem
dict1["2"] = "Two" # this is useing setitem
print(dict1)
class MyDict:
def __init__(self):
self.numbers = {}
def __setitem__(self, key, value):
self.numbers[key] = value
def __getitem__(self, key):
return self.numbers[key]
def __str__(self):
# print(self.numbers)
return f"{self.numbers}"
dict1 = MyDict()
# print(dict1)
dict1.numbers["1"] = "One"
print(dict1.numbers)
dict1["1"] = "One"
print(dict1["1"])