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Chapter 06 constructors and destructors
Constructors and destructors in Python. Constructors are special methods that are called automatically when an object is created. They initialize variables and ensure objects are properly initialized. There are two types of constructors: default and parameterized. Default don't take arguments, parameterized do. Destructors are called when an object is destroyed. Defined using __del__(), they are useful for releasing resources like closing files before a program exits. The document then provides code examples of classes with constructors, parameterized constructors, and destructors. It also discusses Python's garbage collection and how the collector deletes unneeded objects to free memory space.
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Chapter 06 constructors and destructors
- 1. CHAPTER - 06 CONSTRUCTORSAND DESTRUCTORS
- 2. Unit I Programming andComputational Thinking (PCT-2) (80 Theory + 70 Practical) DCSc & Engg, PGDCA,ADCA,MCA.MSc(IT),Mtech(IT),MPhil (Comp. Sci) Department of Computer Science, Sainik School Amaravathinagar Cell No: 9431453730 Praveen M Jigajinni Prepared by Courtesy CBSE Class XII
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- 4. CONSTRUCTOR Constructor is aspecial type of function that is called automatically whenever an object of that class is created. General format or syntax : def __init__(self): # body of the constructor Once the object is created, you can make sure that every variable in the object is correctly initialised by defining an __init__ method in your class, which pretty much means init-iate.
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- 8. TYPES OF CONSTRUCTOR Wehave two types of constructors in Python. 1. default constructor – this is the one, which we have seen in the above example. This constructor doesn’t accept any arguments. 2. parameterized constructor – constructor with parameters is known as parameterized constructor.
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- 13. DESTRUCTOR Destructors are calledwhen an object gets destroyed. It’s the polar opposite of the constructor, which gets called on creation. Destructor can be very useful for releasing resources before coming out of the program like closing files, releasing memories etc Destructor is defined using __del__() keyword
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- 15. DESTRUCTOR Destructor method calledautomatically and object is destroyed
- 16. PYTHON GARBAGE COLLECTION Pythondeletes unneeded objects (built-in types or class instances) automatically to free the memory space. The process by which Python periodically reclaims blocks of memory that no longer are in use is termed as Garbage Collection. Python's garbage collector runs during program execution and is triggered when an object's reference count reaches zero.
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- 18. SOLVIING CBSE QUESTIONPAPER 2(C) 4 Marks PROGRAMS ON CLASSES
- 19. CBSE QUESTION PAPER- 2015 DELHI
- 20. (c) Write aclass PICTURE in Python with following specifications : 4 Instance Attributes – Pno # Numeric value – Category # String value – Location # Exhibition Location with # String value Methods : – FixLocation() # A method to assign # Exhibition Location as per #Category # as shown in the following table CBSE QUESTION PAPER - 2015 DELHI
- 21. – Enter() #A function to allow user to enter values # Pno, Category and call FixLocation() method – SeeAll() # A function to display all the data members Category Location Classic Amina Modern Jim Plaq Antique Ustad Khan CBSE QUESTION PAPER - 2015 DELHI
- 22. CBSE QUESTION PAPER- 2015 OUTSIDE DELHI
- 23. (c) Write aclass PHOTO in Python with following specifications : 4 Instance Attributes – Pno # Numeric value – Category # String Value – Exhibit # Exhibition Gallery with String value Methods: – FixExhibit() #A method to assign #Exhibition Gallery as per #Category #as shown in the following table CBSE QUESTION PAPER - 2015 DELHI
- 24. CBSE QUESTION PAPER- 2015 DELHI Category Exhibit Antique Zaveri Modern Johnsen Classic Terenida -Register() #A function to allow user to enter values #Pno, Category and call FixExhibit() method – ViewAll() #A function to display all the data members
- 25. CBSE QUESTION PAPER- 2016 DELHI
- 26. CBSE QUESTION PAPER- 2016 DELHI (c) Write a class CITY in Python with following specifications : 4 Instance Attributes – Code # Numeric value – Name # String value – Pop # Numeric value for Population – KM # Numeric value – Density # Numeric value for Population Density than 12000.
- 27. CBSE QUESTION PAPER- 2016 DELHI Methods: – CalDen() # Method to calculate Density as Pop/KM – Record() # Method to allow user to enter values Code, Name, Pop, KM and call CalDen() method – See() # Method to display all the data members also display a message “Highly Populated Area” if the Density is more than 12000.
- 28. CLASS TEST 1. Whatis Constructor? Explain 2. What are the types of constructors? 3. What is destructors? Explain 4. Write a program to illustrate constructors 5. Write a program to illustrate distructors Class : XII Time: 40 Min Topic: Const & distruct Max Marks: 20 Each Question carries 4 marks
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