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Python Programming | JNTUA | UNIT 2 | Case Study |
The document discusses Python's turtle module which allows drawing lines by steering turtles around the screen. It can be imported from the Swampy package. The turtle module provides functions like fd, bk, lt, rt for moving the turtle forward, backward, left, right. Simple repetition and encapsulation techniques are demonstrated. Generalization is discussed by adding parameters to functions. Interface design principles around parameters and return values are covered. Refactoring existing code and adding docstrings for documentation are also mentioned.
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- 1. Python Programming Unit –II (Part I) (Lecture 14) Case Study
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- 4. The turtle module •A package is a collection of modules. • One of the modules in Swampy package is TurtleWorld. • It provides a set of functions for drawing lines by steering turtles around the screen.
- 5. The turtle module •If Swampy is installed as a package on your system, you can import TurtleWorld like this: from swampy.TurtleWorld import * • If you downloaded the Swampy modules but did not install them as a package hen you can import TurtleWorld like this: from TurtleWorld import *
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- 7. The turtle module TurtleWorldprovides several turtle- steering functions: • fd and bk for forward and backward • lt and rt for left and right turns. • The functions pu and pd stand for “pen up” and “pen down”.
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- 9. Case study Lecture 14 Theturtle module Simple Repetition
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- 15. Encapsulation • Wrapping apiece of code up in a function is called encapsulation. • Advantage is that if you re-use the code, it is more concise to call a function twice than to copy and paste the body!
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- 17. Generalization • Adding aparameter to a function is called generalization because it makes the function more general: • in the previous version, the square is always the same size; in this version it can be any size.
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- 19. Python Programming Unit –II (Part I) (Lecture 16) Case Study
- 20. Case Study Lecture 14 Theturtle module Simple Repetition Encapsulatio n Generalizatio n Interface design Refactoring docstring Lecture 15 Lecture 16
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- 22. Interface design • nis the number of line segments in our approximation of a circle, so length is the length of each segment. • Thus, polygon draws a 50-sides polygon that approximates a circle with radius r.
- 23. Interface design • Onelimitation of this solution is that n is a constant, which means that for very big circles, the line segments are too long, and for small circles, we waste time drawing very small segments.
- 24. Interface design • Theinterface of a function is a summary of how it is used: • What are the parameters? • What does the function do? • What is the return value?
- 25. Interface design • Nowthe number of segments is (approximately) circumference/3, so the length of each segment is (approximately) 3, • which is small enough that the circles look good, but big enough to be efficient, and appropriate for any size circle.
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- 27. Refactoring We can’t usepolygon or circle to draw an arc.
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