Real word simulation of a Printer using Queue in Python

Question

I am going through the book "Problem Solving with Algorithms and Data Structures using Python"

In the chapter for Queues there is a printer simulation with the Printer class.

here is the definition of Printer class:

class Printer():
def __init__(self, ppm):
    self.pagerate = ppm
    self.currentTask = None
    self.timeRemaining = 0

My question is that how are the instance variable not present in parameter but still defined (e.g. currentTask and timeRemaining)?

Is it a practice in Python and is there any other better way to do this?

http://interactivepython.org/courselib/static/pythonds/BasicDS/SimulationPrintingTasks.html — rahul agarwal, Mar 25 '19 at 18:31
https://docs.python.org/3/reference/datamodel.html#object.__init__ — Patrick Artner, Mar 25 '19 at 19:07

score 0 · Answer 1 · edited Mar 25 '19 at 19:08

From the documentation https://docs.python.org/3/tutorial/classes.html#class-objects

The instantiation operation (“calling” a class object) creates an empty object. Many classes like to create objects with instances customized to a specific initial state. Therefore a class may define a special method named __init__(), like this:
def __init__(self):
    self.data = []

Also Instance variables vs. class variables in Python

Protik Nag · Answer 2 · 2019-03-26T19:57:11.180

0

You don't need to pass values for all parameters. By writing self.variable_name we automatically create instance variables. They don't need to be initiated with passed values. You can initiate them with None values.

edited Mar 26 '19 at 19:57

answered Mar 25 '19 at 19:06

Protik Nag

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well none of the documents provided here answer my question.But I guess i can take away from this question that i can create variable w/o passing values.Maybe I did not frame the question right. – rahul agarwal Mar 25 '19 at 19:27

Real word simulation of a Printer using Queue in Python

2 Answers2