Building a Polar Point From Cartesian Coordinates
00:00 Building a Polar Point From Cartesian Coordinates. For a more elaborate example of providing multiple constructors using class methods, let’s say you have a class representing a polar point in a math-related application.
00:15 You need a way to make your class more flexible so that you can construct new instances using Cartesian coordinates as well. On-screen, you can see how to write a constructor to meet this requirement.
.from_cartesian() takes two arguments representing a given point’s
y Cartesian coordinates. Then the method calculates the required
angle to construct the corresponding
.from_cartesian() returns a new instance of the class.
01:36 On-screen, you can see the class working using both coordinate systems. First you create a point using polar coordinates, and then one using Cartesian coordinates.
In these examples, you use the standard instantiation process and your alternative constructor,
.from_cartesian(), to create
PolarPoint instances using conceptually different initialization arguments.
02:10 In the next section of the course, you’ll take a closer look at the use of multiple constructors in Python’s built-in and standard-library classes.
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