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: