ask-nicely

ASK-NICELY

Easily create command-line applications by configuring commands, options and parameters that are supermagically parsed.

Ask Nicely is different from parsers like minimist because it interprets input based on what's configured, rather than syntax alone.

Example

An elaborate example can be found in examples/application.annotated.js. The following code is a functioning command-line application (that merely dumps whatever Request object was parsed from input):

import { Command } from 'ask-nicely';

const root = new Command();

root.addOption('alpha', 'a');

root.addCommand('subcommand', request => {
		console.log(request));
		return { somethingWasDone: true };
	})
	.addOption('beta', 'b', 'Beta is the second letter of the greek alphabet', true)
	.addParameter('gamma');

root.execute(process.argv.slice(2))
	.then(result => console.log(result))
	.catch(error => console.log(error));

Parsing input (process.argv in this example) would yield the following Request object in the relevant controller and precontrollers:

// node examples/application.microscopic.js -a
{
    command:    { /* the root command */ },
    options:    { alpha: true }
}

// node examples/application.microscopic.js subcommand paramValue --beta optValue
{
    command:    { /* the subcommand */ },
    parameters: { gamma: 'paramValue' },
    options:    { alpha: undefined, beta: 'optValue' }
}

Advanced use

The Command methods addOption and addParameter either take a couple of strings and booleans, or an Option or Parameter instance respectively. Creating the instance of Option or Parameter first allows you to configure it with more advanced behaviour.

There are different kinds of Options and Parameters; for example, --user.name wvbe would create an object (req.options.user = { name: 'wvbe' }) if you configure it as a DeepOption. These extending Option and Parameter classes are exposed on AskNicely and it's instances.

import { Option } from 'ask-nicely';

root.addOption(new Option('delta')
    .setShort('d')
    .setResolver(input => database.find('users', input))
    .addValidator(user => {
        if (user.username === 'wvbe')
            throw new Error('Get this sucka outta here');
    })
);

The resolver transforms flat text input into something different and is handled asynchronously if it returns a Promise. The validator in the example would throw a custom error if the resolved user object happens to have my username.

Important classes

• Command
• Option
  • MultiOption (like --emails [e-mail] [e-mail])
  • DeepOption (like --config.username wvbe)
  • IsolatedOption (like --help, prevents further input parsing)
• Parameter
  • DeepParameter (as seen in git config)
• Request (user input is assigned to this object)
• InputError (thrown if a mistake was made by the end-user rather than a programmer)

Important methods

• Command, Option and Parameter classes (NamedSyntaxPart)
  • constructor(name)
  • addAlias(alias)
  • setDescription(description)
• Option and Parameter classes (VariableSyntaxPart)
  • isRequired(required)
  • addValidator(validator)
  • setResolver(resolver)
• Parameter classes
  • setDefault(arbitrary)
• Option classes
  • setDefault(arbitrary, useDefaultIfFlagMissing)
  • setShort(short)
• MultipleOption class
  • isInfinite(infinite))
• Command classes
  • addCommand(command|name[, controller])
  • addOption(option|name[, short, description, required])
  • addParameter(parameter|name[, description, required])
  • addPreController(controller)
  • execute(input, [request, ...arbitrary])
  • parse(input, [request, ...arbitrary])
  • setController(controller)
  • setNewChildClass(Class)
• Request class
  • constructor()
  • execute([...arbitrary])

Behaviour

• Input for Options or Parameters can contain spaces if the input is wrapped in double-quotes (--opt "My option")
• Options and Parameters accumulate as you go deeper from root into subcommands. In this way, any command can add scope to the underlying subcommands through the Request object
• Precontrollers (Command#addPrecontroller()) are accumulated as you go deeper into subcommands as well. When a command is ran, all of it's ancestors precontrollers are ran too. In this way, for example, a precontroller can determine if the execution chain should stop for a certain combination of options (by returning false).
• With exception of DeepOption, Option classes with a default value will stay undefined, unless you set the second argument of Option#setDefault() to true.
• Arbitrary arguments to AskNicely#interpret() and Request#execute() are passed down to syntax resolvers, precontrollers and controllers. This allows you to pass an application/config object along.

Release notes

• v 4.0.0
  • Fixed an issue where the most specifically defined Option (ie. on the deepest command) of the same name did not win.
• v 3.0.0
  • Deprecate the Root class, any Command can serve as root
  • Refactor Root#interpret() to Command#parse(), which doesn't throw and parses more
  • Add Command#execute() which parses, executes, and throws like the previous interpret method would have.
• v 2.0.0
  • Expose classes as an ES6 module
  • Package using rollup and babel ES2015 preset
  • Rename the AskNicely (root class) to Root
  • Do not expose the root class as a default export
  • Do not expose classes via an instance of ask-nicely
• v 1.1.1
  • Fix the way InputError was exposed
• v1.1.0
  • Adding Command#addAlias(alias)
  • Throwing new InputError as opposed to regular Error in some cases, allows you do distinguish user errors from system errors.
  • Exposing Request and allow to use pass own instance to AskNicely#interpret()
  • Adding Command#setController(controller) and #setNewChildClass(Class)
  • Declaring properties on Request in constructor so you don't have to keep null-checking
  • Adding MultiOption class, which evaluates to an array
• v1.0.0
  • Using ECMAScript 6
  • Option, Parameter and related classes increase configurability a thousandfold
  • Moved most parsing logic to individual classes that represent a syntax part
  • AskNicely#interpret() is no longer synchronous because of the ability to asynchronously resolve values
  • Ditching a lot of useless methods that are not directly used for parsing or configuring, moving a lot of other stuff
  • Ditching Command#isHungry() and Command#isGreedy()
• v0.1.0
  • Initial release, pretty basic parsing with limited configurability

Issues/known bugs

• There's a problem in VariableSyntaxPart that would fail to clone the default property object of a DeepOption of DeepParameter, resulting in changes to the default value that is shared with other instances of that syntax part. As a work-around the default object is stringified and parsed again, therefore it is limited to something that can be serialized.
• Your terminal may replace patterns (like "*") with an actual list of matching file names before the node process is even started. This prevents parsing those patterns in AskNicely, and may yield unexpected results. Seen in gnome-terminal using oh-my-zsh. Can be circumvented by enclosing input data in double quotes, although that's kind of shitty.

Wishlist

• Fix aforementioned issues and known bugs.
• DeepOption with a default value should stay undefined if flag is not set, like rest of Option classes.
• Implement isInfinite() for other VariableSyntaxPart classes
• Implement addAlias() for all NamedSyntaxPart classes, maybe.
• A different way of stopping the controller chain, returning FALSE is a little crude
• Make it easy for commands to call other commands, maybe in a dependency-aware manner
• Test more edge cases, like conflicts and multiple values

License

Copyright (c) 2015 Wybe Minnebo

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.