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Commit 7cb55c0

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Encapsulation
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4 files changed

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‎06.Encapsulation/encapsulation-1.py

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#encapsulation-1.py
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# Encapsulation means to preserve data in classes using methods
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# Here, we're setting the 'val' attribute through 'set_val()'.
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# See the next example, `encapsulation-2.py` for more info
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# In this example, we have two methods, `set_val` and `get_val`.
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# The first one sets the `val` value while the second one
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# prints/returns the value.
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class MyClass(object):
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def set_val(self, val):
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self.value = val
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def get_val(self):
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# print(self.value)
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return self.value
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a = MyClass()
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b = MyClass()
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a.set_val(10)
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b.set_val(100)
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a.get_val()
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b.get_val()
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# NOTE: If you run this code, it won't print anything to the screen.
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# This is because, even if we're calling `a.get_val()` and `b.get_val()`,
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# the `get_val()` function doesn't contain a `print()` function.
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# If we want to get the output printed to screen, we should do any of
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# the following:
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# a) Either replace `return self.value` with `print(self.value)`
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# or add a print statement **above** `return` as `print(self.value)`.
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# b) Remove `return(self.value)` and replace it with `print(self.value)`

‎06.Encapsulation/encapsulation-2.py

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#encapsulation-2.py
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# This example builds on top of `encapsulation-1.py`.
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# Here we see how we can set values in methods without
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# going through the method itself, ie.. how we can break
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# encapsulation.
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# NOTE: BREAKING ENCAPSULATION IS BAD.
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class MyClass(object):
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def set_val(self, val):
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self.value = val
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def get_val(self):
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print(self.value)
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a = MyClass()
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b = MyClass()
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a.set_val(10)
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b.set_val(1000)
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a.value = 100 # <== Overriding `set_value` directly
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# <== ie.. Breaking encapsulation
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a.get_val()
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b.get_val()
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'''
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O/P-
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100
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1000
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'''

‎06.Encapsulation/encapsulation-3.py

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#encapsulation-3.py
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# Here we look at another example, where we have three methods
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# set_val(), get_val(), and increment_val().
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# set_val() helps to set a value, get_val() prints the value,
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# and increment_val() increments the set value by 1.
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# We can still break encapsulation here by calling 'self.value'
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# directly in an instance, which is **BAD**.
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# set_val() forces us to input an integer, ie.. what the code wants
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# to work properly. Here, it's possible to break the encapsulation by
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# calling 'self.val` directly, which will cause unexpected results later.
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# In this example, the code is written to enforce an intger as input, if we
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# don't break encapsulation and go through the gateway 'set_val()'
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#
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class MyInteger(object):
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def set_val(self, val):
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try:
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val = int(val)
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except ValueError:
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return
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self.val = val
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def get_val(self):
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print(self.val)
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def increment_val(self):
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self.val = self.val + 1
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print(self.val)
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a = MyInteger()
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a.set_val(10)
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a.get_val()
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a.increment_val()
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print("Before Break")
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# Trying to break encapsulation in a new instance with an int
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c = MyInteger()
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c.val = 15
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c.get_val()
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c.increment_val()
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print("After Break")
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# Trying to break encapsulation in a new instance with a str
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b = MyInteger()
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b.val = "MyString" # <== Breaking encapsulation, works fine
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b.get_val() # <== Prints the val set by breaking encap
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b.increment_val() # This will fail, since str + int wont work
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print("Changing DataType")
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'''
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O/P-
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10
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11
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Before Break
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15
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16
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After Break
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MyString
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Traceback (most recent call last):
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self.val = self.val + 1
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TypeError: can only concatenate str (not "int") to str
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'''

‎README.md

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02. [Methods-Functions](https://github.com/Shikha-code36/Object-Oriented-Programming-OOPs-Python#02-methodsfunctions)
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03. [Objects](https://github.com/Shikha-code36/Object-Oriented-Programming-OOPs-Python#03-objects)
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04. [Constructors](https://github.com/Shikha-code36/Object-Oriented-Programming-OOPs-Python#04-constructors)
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05. [Inheritance](https://github.com/Shikha-code36/Object-Oriented-Programming-OOPs-Python#04-constructors)
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05. [Inheritance](https://github.com/Shikha-code36/Object-Oriented-Programming-OOPs-Python#05-inheritance)
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06. [Encapsulation](https://github.com/Shikha-code36/Object-Oriented-Programming-OOPs-Python#06-encapsulation)
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------------
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## What do you understand by OOPs?
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[Detailed Explanation](05.Inheritance)
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------------
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#### 06. Encapsulation
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Encapsulation involves the bundling of data members and functions inside a single class. Bundling similar data members and functions inside a class also helps in data hiding. Encapsulation also ensures that objects are self-sufficient functioning pieces and can work independently.
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[Detailed Explanation](06.Encapsulation)
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------------

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