Example

Following is the full code listing from the final step of the tutorial. See the design sketch for what this code is meant to accomplish.

#!bin/python
# -*- coding: utf-8; mode: python -*-
import json
import os
import sys

from clik import app, args, g, parser


def print_list():
    for i, item in enumerate(g.item_list):
        print('%i. %s' % (i, item))


@app
def todo():
    """
    Simple application for managing a todo list.

    The data is stored as a JSON file, which defaults to todo.json.
    See above for more information about arguments and subcommands.
    """
    parser.add_argument(
        '-f',
        '--file',
        default='todo.json',
        help='file in which to store data (default: %(default)s)',
    )

    yield

    g.item_list = []
    if os.path.exists(args.file):
        with open(args.file) as f:
            g.item_list = json.load(f)

    yield

    with open(args.file, 'w') as f:
        json.dump(g.item_list, f, indent=2)
        f.write('\n')


@todo.bare
def bare():
    yield
    print_list()


@todo
def add():
    """Add an item to the todo list."""
    parser.add_argument(
        'item',
        help='item to add to do the todo list',
        nargs='?',
    )

    yield

    item = args.item
    if item is None:
        item = input('Item to add: ')
    if item:
        g.item_list.append(item)
    else:
        print('error: empty item', file=sys.stderr)
        yield 1

    print()
    print('Updated list:')
    print_list()


@todo(name='list', alias='ls')
def list_():
    """Show the items on the todo list."""
    yield
    print_list()


@todo
def done():
    """Remove an item from the todo list."""
    group = parser.add_mutually_exclusive_group()
    group.add_argument(
        '-a',
        '--all',
        action='store_true',
        default=False,
        help='mark all items as complete',
    )
    group.add_argument(
        '-i',
        '--index',
        help='integer index of the item to mark as complete',
        type=int,
    )

    yield

    if args.all:
        del g.item_list[:]
    else:
        index = args.index
        while index is None:
            print()
            print_list()
            print()
            selection = input('Index of item to delete? ')
            try:
                index = int(selection)
            except ValueError:
                print('error: invalid int value:', selection, file=sys.stderr)
        if -1 < index < len(g.item_list):
            del g.item_list[index]
        else:
            print('error: index out of bounds:', index, file=sys.stderr)
            yield 1

    print()
    print('Updated list:')
    print_list()


if __name__ == '__main__':
    todo.main()