Passing parameters in Python

To develop this task, the best thing is to use the argparse module that comes installed by default when you install Python.

The following is an example of how to use it in our scripts:

You can find the following code in the filename testing_parameters.py

import argparse

parser = argparse.ArgumentParser(description='Testing parameters')
parser.add_argument("-p1", dest="param1", help="parameter1")
parser.add_argument("-p2", dest="param2", help="parameter2")
params = parser.parse_args()
print params.param1
print params.param2

In the params variable, we have the parameters that the user has entered from the command line. To access them, you have to use the following:

params.<Name_dest>

 One of the interesting options is that it is possible to indicate the type of parameter with the type attribute. For example, if we want a certain parameter to be treated as if it were an integer, we could do it in the following way:

parser.add_argument("-param", dest="param", type="int")

Another thing that could help us to have a more readable code is to declare a class that acts as a global object for the parameters:

class Parameters:
 """Global parameters"""
    def __init__(self, **kwargs):
        self.param1 = kwargs.get("param1")
        self.param2 = kwargs.get("param2")

For example, if we want to pass several parameters at the same time to a function, we could use this global object, which is the one that contains the global execution parameters. For example, if we have two parameters, we can construct the object in this way:

You can find the below code in the filename params_global.py

import argparse

class Parameters:
 """Global parameters"""

    def __init__(self, **kwargs):
        self.param1 = kwargs.get("param1")
        self.param2 = kwargs.get("param2")

def view_parameters(input_parameters):
    print input_parameters.param1
    print input_parameters.param2

parser = argparse.ArgumentParser(description='Passing parameters in an object')
parser.add_argument("-p1", dest="param1", help="parameter1")
parser.add_argument("-p2", dest="param2", help="parameter2")
params = parser.parse_args()
input_parameters = Parameters(param1=params.param1,param2=params.param2)
view_parameters(input_parameters)

In the previous script, we can see that we obtain parameters with the argparse module and we encapsulate these parameters in an object with the Parameters class.With this practice, we get encapsulated parameters in an object to facilitate the retrieval of these parameters from different points of the script.