squirrel

A furry little helper for dealing with optional NPM dependencies

squirrel

Squirrel is a helpful node module that assists you requiring your dependencies for plugins of your application (version controlled via a custom pluginDependencies in your package.json file).

Because personally, I really don't like the sitting waiting for a node package to install a whole swag of dependencies because it requires them for some functionality that I don't intend to use. I believe using squirrel will enable certain types of packages to have a leaner core with properly managed and installable optional dependencies.

If you are using optionalDependencies in your application, you might consider using pluginDependencies instead and then "squirreling" them rather than requiring them.

NOTE: Squirreling is an asynchronous operation:

var squirrel = require('squirrel');
 
squirrel('coffee-script', function(errcoffee) {
  // do something magical with coffeescript... 
});

If you need multiple modules, then squirrel is happy to play in a way similar to the way AMD module loaders do:

squirrel(['coffee-script', 'jade'], function(errcoffeejade) {
  // do something with both coffeescript and jade... 
});

Squirrel has been built to support a number of "Allow Install" modes, which is controlled in an allowInstall option that the squirrel function accepts in the 2nd argument, e.g.:

// install jade, and don't trigger a prompt if not already available 
squirrel('jade', { allowInstall: true }, function(errjade) {
});

The default setting for the allowInstall option is set to prompt which means that when a module using squirrel attempts to squirrel one or more modules, the user will be prompted if they want to allow those modules to install. If they don't permit installation then the squirrel operation will fail and an error will be returned in the callback.

Other valid settings for the allowInstall option are true (install dependencies without prompting) or false (always reject module requests).

A squirrel's got to have options. The demands on the modern squirrel mean that having options is important, and this squirrel is not different. Here are the options that squirrel supports in a 2nd (optional) argument.

  • allowInstall - as outlined above.
  • promptMessage - 'Package "<%= target %>" is required. Permit install? '
  • cwd - the path to squirrel in
  • installer - 'npm'
  • installCommand - '<%= opts.installer %> install <%= target %>@<%= version %>'
  • uninstallCommand - '<%= opts.installer %> rm <%= target %>'

The default options can be modified through modifying them in the squirrel.defaults object.

You could argue that given squirrel's mission is to reduce the overall number of package dependencies, it should be ultralight in it's own packaging. While that's a valid point, I think a balance is required and using existing well-tested libraries is important.

Request the installation of the modules specified in the targets array argument.

Remove the specified targets. Used in squirrel tests and I guess in some cases might be useful in production code also.

This module constains the installer helper functions used within squirrel. Each of the functions outlined below is designed to be called initially with an options object, which then provides you the function signature outlined in the docs.

var installer = require('squirrel/installer');

Use npm to install the required target.

This is the first step called in the pull-stream when squirrel is asked for particular modules. It will determine what action is required based on what has been asked for, depending on a number of factors:

  • whether the module requested is relative (i.e. starts with a dot)
  • what our allowed install options (prompt, always, never, etc)
  • whether the module is already available or not

Execute the required installer operation

Copyright (c) 2014 Damon Oehlman damon.oehlman@gmail.com

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