Candela is a simple shell-building system that uses python and curses to help developers create customized command line interfaces. It has a simple interface, is well documented, and allows developers to take command-based tools to the next level of complexity and usability.

• Commands are 100% python and can run aribtrary code
• Commands can run code in secondary threads for asynchronous operation
• Responsive layout for smaller terminals
• Numerous built-in command templates
• Simple command syntax and help system
• "stickers" allow persistent information display
• Automatically generated command validation
• Up/Down arrows cycle through history
• Copy/Paste, insert text mode
• Easy transitions between menus
• Supports both named and positional command arguments

There is an example shell project in shell_example.py. To run it, use

python shell_example.py

in a maximized terminal window.

Download the source from PyPI with

pip install candela

You can also clone this repo to take a closer look at the code and demo app.

git clone https://github.com/emmett9001/candela.git

Then, install the library with

python setup.py install

Import Candela commands, menus, and the shell

from candela.shell import Shell
from candela.menu import Menu
from candela.command import Command
from candela import constants

Alternatively, you can simply import candela and reference the components with candela.shell.Shell, etc.

Every Candela app is built as a subclass of candela.shell.Shell. A Shell initialization follows this general outline:

• Set self.name
• Set self.header
• Define and instantiate Commands
• Define and instantiate Menus
• Add Commands to Menus
• Set self.menus to contain instantiated Menus
• Set self.menu to be the name of the default menu

In general, a command instantiation looks like this

com = Command('first_command', 'Intro to commands')
def _run(*args, **kwargs):
    # do anything
    return constants.CHOICE_VALID
com.run = _run
return com

Functions that execute on command invocation are modeled as python first-class functions (callbacks).

Please see the shell example for a full walkthrough of how to use Candela. This example is both well-commented and an instructional app demonstrating Candela's features.

The name "Candela" was chosen after Spanish architect Felix Candela, who pioneered the technique of building shell-shaped structures out of reinforced concrete. He is sometimes known as the "shell builder".

If you need help using Candela, or have found a bug, please create an issue on the Github repo.

Copyright 2013 Emmett Butler

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.