Defining and Using Coroutines in Python: A Complete Guide

1. Defining a Coroutine in Python

• Define a coroutine function 'linear_equation' which takes two arguments 'a' and 'b'.

• Any coroutine derived from 'linear_equation' should be capable of taking a number as input, and evaluating the expression 'a*(x**2)+ b'.

• The couroutine after evaluating the expression should print the message 'Expression, 3*x^2+4, with x being 6 equals 112'.

Hint: Use print() instead of 'return', to print the output.

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Solutions

#!/bin/python3

import sys


# Define the coroutine function 'linear_equation' below.

def linear_equation(a, b):

    while True:

        x=yield

        c=a*(pow(x,2))+b

        print('Expression, '+str(a)+'*x^2 + '+str(b)+', with x being '+str(x)+ ' equals '+str(c))


if __name__ == "__main__":
    a = float(input())

    b = float(input())

    equation1 = linear_equation(a, b)
    
    next(equation1)
    
    equation1.send(6)
    
     

2. Give a Try - Define a Decorator for Coroutine

• Define a Decorator 'coroutine_decorator', which can decorate any coroutine function.

• The decorator must create the coroutine, call 'next' on it and return the coroutine that is ready for accepting any input.

• For e.g

@coroutine_decorator def linear_equation(a,b):

e1 = linear_equation(3, 4) # e1 should able to accept input without calling 'next' on it. e1.send(6)

 

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Solution

import sys

import os

# Define 'coroutine_decorator' below

def coroutine_decorator(coroutine_func):

    def wrapper(*args, **kwdargs):

        c = coroutine_func(*args, **kwdargs)

        next(c)

        return c

    return wrapper

    

# Define coroutine 'linear_equation' as specified in previous exercise

@coroutine_decorator

def linear_equation(a, b):

    while True:

        x=yield

        c=a*(pow(x,2))+b

        print('Expression, '+str(a)+'*x^2 + '+str(b)+', with x being '+str(x)+ ' equals '+str(c))
    
if __name__ == "__main__":
    a = float(input())

    b = float(input())

    equation1 = linear_equation(a, b)
    
    equation1.send(6)
    
    

3. Give a Try - Linking two coroutines

• Define 'linear_equation' and 'coroutine_decorator' functions as requested in previous test case.

• Define a coroutine function 'numberParser', which is capable of converting the passed input into an integer and also sends the integers to two linear equation coroutines equation1 and 'equation2`.

• 'equation1' represents linear equation coroutine with a = 3 and b = 4

'equation2' represents linear equation coroutine with a = 2 and b = -1

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#!/bin/python3


import sys


# Define the function 'coroutine_decorator' below

def coroutine_decorator(coroutine_func):

    def wrapper(*args, **kwdargs):

        c = coroutine_func(*args, **kwdargs)

        next(c)

        return c

    return wrapper

    

# Define the coroutine function 'linear_equation' below

@coroutine_decorator

def linear_equation(a, b):

    while True:

        x=yield

        c=a*(pow(x,2))+b

        print('Expression, '+str(a)+'*x^2 + '+str(b)+', with x being '+str(x)+ ' equals '+str(c))

    

# Define the coroutine function 'numberParser' below

@coroutine_decorator

def numberParser():

    equation1 = linear_equation(3, 4)

    equation2 = linear_equation(2, -1)

    # code to send the input number to both the linear equations

    while True:

        m=yield

        equation1.send(m)

        equation2.send(m)

    

def main(x):

    n = numberParser()

    n.send(x)
    
if __name__ == "__main__":
    x = float(input())

    res = main(x);