def divide(a, b):
try:
return a/b
except ZeroDivisionError:
return("Division by zero isn't possible")
except TypeError:
return("Unsupported type error")
print(divide(10, 3))Tag: python
How to handle errors with try and except by using else and finally in Python
- If try throws an error then except executes.
- If try doesn’t throw an error then else part executes.
- The finally block executes always. Error doesn’t matter here.
while True:
try:
age = int(input("Enter the age to check eligibility : "))
break
except ValueError:
print("Please enter an integer")
except:
print("Unexpected error")
else:
print(f"User has entered {age}")
finally:
print("This is a program to verify age")
if age>18:
print("You are eligible to play")
else:
print("You aren't eligible to play")Handling Exception with try and except in Python
while True:
try:
age = int(input("Enter the number to check eligibility : "))
break
except ValueError:
print("You might have entered string. Try integer value. Try again please...")
except:
print("Unexpected error")
if(age>18):
print("You are eligibile to play the game!!")
else:
print("You are not eligible to play the game!!")Raising Errors with Python and understanding the concept of Abstract Methods
- There are no abstract methods in Python.
- The name came from JAVA Programming Language. But we can raise error to implement that kind of methods in Python too.
class Phone:
def __init__(self, brand, model):
self.brand = brand
self.model = model
def cameraa(self):
raise NotImplementedError("This method must be defined in each and every subclass")
class SmartPhone(Phone):
def __init__(self, brand, model, camera):
super().__init__(brand, model)
self.camera = camera
class FlagshipPhone(Phone):
def __init__(self, brand, model, front_camera, rear_camera):
super().__init__(brand, model)
self.front_camera = front_camera
self.rear_camera = rear_camera
S = SmartPhone("POCO", "X2", "64MP")
print(S.cameraa())OUTPUT :
Traceback (most recent call last):
File "c:/Users/dsaya/OneDrive/Desktop/PythonPractise/OOP/RaiseError.py", line 21, in <module>
print(S.cameraa())
File "c:/Users/dsaya/OneDrive/Desktop/PythonPractise/OOP/RaiseError.py", line 7, in cameraa
raise NotImplementedError("This method must be defined in each and every subclass")
NotImplementedError: This method must be defined in each and every subclassDunder methods, Operator Overloading, Polymorphism in Python
class Phone:
def __init__(self, brand, model_name, price):
self.brand = brand
self.model_name = model_name
self.price = price
def full_name(self):
return f"This phone is {self.brand} {self.model_name}"
def make_a_call(self, number):
return f"Dialling {number}..."
class Smartphone(Phone):
def __init__(self, brand, model_name, price, ram, internal_memory, rear_camera):
super().__init__(brand, model_name, price)
# Phone.__init__(self, brand, model_name, price)
self.ram = ram
self.internal_memory = internal_memory
self.rear_camera = rear_camera
def full_name(self):
return f"This phone is {self.brand} {self.model_name} and it has a rear camera of {self.rear_camera}"
class Flagshipphone(Smartphone):
def __init__(self, brand, model_name, price, ram, internal_memory, rear_camera, front_camera):
super().__init__(brand, model_name, price, ram, internal_memory, rear_camera)
self.front_camera = front_camera
def full_name(self):
return f"This phone is {self.brand} {self.model_name} and it has a front camera of {self.front_camera}"
def __str__(self):
return f"{self.brand} {self.model_name}"
def __repr__(self):
return f"{self.brand} {self.model_name}"
def __len__(self):
return len(self.full_name())
def __add__(self, other):
return int(self.price) + int(other.price)
S1 = Flagshipphone("OnePlus", "8 Pro", "75000", "8GB", "256GB", "64MP", "32MP")
S2 = Flagshipphone("OnePlus", "7 Pro", "76000", "8GB", "256GB", "64MP", "32MP")
# S2 = Flagshipphone("OnePlus", "8 Pro", "75000", "8GB", "256GB", "64MP", "32MP")
# print(S2.full_name())
# print(help(Smartphone))
# print(S1.__repr__())
# print(str(S1))
print(S1.__len__())
print(S1 + S2)Protected: Project on Indian Railways
Multiple Inheritance in Python
- This is something that is mostly not used by developers due to the confusion it causes.
- It has a main problem with order. In the order, which comes first will be called first.
- As in the example below, if we want to print the hello method of Class B, we need to inherit the B class first from the C class.
class A:
def class_a_method(self):
return "This is a method of Class A"
def hello(self):
return "Returning from Class A"
class B:
def class_a_method(self):
return "This is a method of Class A"
def hello(self):
return "Returning from Class B"
class C(A, B):
pass
objC = C()
print(objC.hello())
print((help(C))
OUTPUT:
Returning from Class A
Help on class C in module __main__:
class C(A, B)
| Method resolution order:
| C
| A
| B
| builtins.object
|
| Methods inherited from A:
|
| class_a_method(self)
-- More --Checking Method Resolution Order (MRO) in Python
class Phone:
def __init__(self, brand, model_name, price):
self.brand = brand
self.model_name = model_name
self.price = price
def full_name(self):
return f"This phone is {self.brand} {self.model_name}"
def make_a_call(self, number):
return f"Dialling {number}..."
class Smartphone(Phone):
def __init__(self, brand, model_name, price, ram, internal_memory, rear_camera):
super().__init__(brand, model_name, price)
# Phone.__init__(self, brand, model_name, price)
self.ram = ram
self.internal_memory = internal_memory
self.rear_camera = rear_camera
def full_name(self):
return f"This phone is {self.brand} {self.model_name} and it has a rear camera of {self.rear_camera}"
class Flagshipphone(Smartphone):
def __init__(self, brand, model_name, price, ram, internal_memory, rear_camera, front_camera):
super().__init__(brand, model_name, price, ram, internal_memory, rear_camera)
self.front_camera = front_camera
def full_name(self):
return f"This phone is {self.brand} {self.model_name} and it has a front camera of {self.front_camera}"
S1 = Smartphone("OnePlus", "8 Pro", "75000", "8GB", "256GB", "64MP")
S2 = Flagshipphone("OnePlus", "8 Pro", "75000", "8GB", "256GB", "64MP", "32MP")
print(S2.full_name())
print(help(Smartphone))Output :
Help on class Smartphone in module __main__:
class Smartphone(Phone)
| Smartphone(brand, model_name, price, ram, internal_memory, rear_camera)
|
| Method resolution order:
| Smartphone
| Phone
| builtins.object
|
| Methods defined here:
|
-- More --Multilevel Inheritance and Method Overriding in Python
class Phone:
def __init__(self, brand, model_name, price):
self.brand = brand
self.model_name = model_name
self.price = price
def full_name(self):
return f"This phone is {self.brand} {self.model_name}"
def make_a_call(self, number):
return f"Dialling {number}..."
class Smartphone(Phone):
def __init__(self, brand, model_name, price, ram, internal_memory, rear_camera):
super().__init__(brand, model_name, price)
# Phone.__init__(self, brand, model_name, price)
self.ram = ram
self.internal_memory = internal_memory
self.rear_camera = rear_camera
def full_name(self):
return f"This phone is {self.brand} {self.model_name} and it has a rear camera of {self.rear_camera}"
class Flagshipphone(Smartphone):
def __init__(self, brand, model_name, price, ram, internal_memory, rear_camera, front_camera):
super().__init__(brand, model_name, price, ram, internal_memory, rear_camera)
self.front_camera = front_camera
def full_name(self):
return f"This phone is {self.brand} {self.model_name} and it has a front camera of {self.front_camera}"
S1 = Smartphone("OnePlus", "8 Pro", "75000", "8GB", "256GB", "64MP")
S2 = Flagshipphone("OnePlus", "8 Pro", "75000", "8GB", "256GB", "64MP", "32MP")
print(S1.full_name())
print(S2.full_name())Inheritance in Python (2nd Method)
class Phone:
def __init__(self, brand, model_name, price):
self.brand = brand
self.model_name = model_name
self.price = price
@property
def full_name(self):
return f"This phone is {self.brand} {self.model_name}"
def make_a_call(self, number):
return f"Dialling {number}..."
class Smartphone(Phone):
def __init__(self, brand, model_name, price, ram, internal_memory, rear_camera):
Phone.__init__(self, brand, model_name, price)
self.ram = ram
self.internal_memory = internal_memory
self.rear_camera = rear_camera
S1 = Smartphone("OnePlus", "8 Pro", "75000", "8GB", "256GB", "64MP")
print(S1.full_name)
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