Getting started with CPL

Welcome to CPL!

This tutorial introduces you to the essentials of the CPL package by walking through building an console based app.

Table of Contents

Prerequisites
Create the project
Create a menu
What’s next

Prerequisites

To get most out of this tutorial you should already have a basic understanding of the following.

Python

Also you need to have the following installed.

Create the project

To create the sample project to the following:

Open a terminal
Run
```
cpl new console sample-project
```

We don’t want to use Application base or Dependency injection:

Do you want to use application base? (y/n) n

Do you want to use service providing? (y/n) n

The ouput should look like this:

Creating sample-project/LICENSE                                                                     done
Creating sample-project/README.md                                                                   done
Creating sample-project/src/tests/__init__.py                                                       done
Creating sample-project/appsettings.json                                                            done
Creating sample-project/src/sample-project/__init__.py                                              done
Creating sample-project/src/sample-projectmain.py                                                   done

Open the project with an IDE like VS Code or PyCharm
Set the ‘src’ directory as source folder
Run the application

You should see an output like:
```
Hello World
```
In PyCharm you have to enable Emulate terminal in output console!

Create a menu

Open the ‘sample-project/main.py’
Change ‘Hello World’ to ‘Password generator:’ in line 5

Add Console.select as follows:

from cpl_core.console import Console


def main():
    Console.write_line('Password generator:')
    options = [
        'Only lower case',
        'Only upper case',
        'Lower and upper case'
        'Exit'
    ]
    option = Console.select('>', 'Select option: ', options)


if __name__ == '__main__':
    main()

Get Id of the selected option:
```
index = options.index(option)
```

Create the generate function as follows:

def generate_password(letters: str, length: int) -> str:
    return ''.join(random.choice(letters) for i in range(length))

Add imports:

import random
import string

Get length of the password:
```
length = int(Console.read('Length: '))
```

Validate the selected option:

index = options.index(option)
letters = ''

if index == 0:
    letters = string.ascii_lowercase
elif index == 1:
    letters = string.ascii_uppercase
elif index == 2:
    letters = string.ascii_letters
elif index == len(options) - 1:
    exit()

Print the generated password:

Console.write_line('Password: ', generate_password(letters, length))

The full ‘sample-project/main.py’:

import random
import string

from cpl_core.console import Console


def generate_password(letters: str, length: int) -> str:
    return ''.join(random.choice(letters) for i in range(length))


def main():
    Console.write_line('Password generator:')
    options = [
        'Only lower case',
        'Only upper case',
        'Lower and upper case',
        'Exit'
    ]
    option = Console.select('>', 'Select option: ', options)

    length = int(Console.read('Length: '))

    index = options.index(option)
    letters = ''
    if index == 0:
        letters = string.ascii_lowercase
    elif index == 1:
        letters = string.ascii_uppercase
    elif index == 2:
        letters = string.ascii_letters
    elif index == len(options) - 1:
        exit()

    Console.write_line('Password: ', generate_password(letters, length))


if __name__ == '__main__':
    main()

What’s next

In this section, you’ve created an application that uses user input to generate a password.

To continue exploring CPL and developing applications: