A cascading filesystem is an elegant solution to a common problem: how to provide a mechanism for loading modules and reusing code?

See my blog post for details:

The load order for my implementation is:

Application path – files under ./application/ are always checked first. Module paths – set modules(['./modules/my-module']) to enable module loading. Files from modules are loaded from in the order they are added. System path – files under ./system/ are loaded if no alternative exists. Assumptions about file and class names

Files are assumed to be lowercase. Underscores in class names are replaced by slashes (so Controller_User becomes ./application/classes/ controller/user.js).

Requests are cached, so that additional calls to find_file() do not cause additional stat() calls in the filesystem. This is insignificant anyway, since Node.js servers are persistent so the cascading search is only done once per server instance for each file (not once per request).

The loaded files do not need to be “compatible” in any way other than layout in the file system. For example, while Hmvc.factory(‘some_other_lib’) loads the file from ./application/ classes/some/other/lib.js, that file does not actually need to contain a class named some_other_lib; just that it returns something via module.exports.

The methods are:

Hmvc.modules(['./modules/path-to-module']) – set the modules directories to search. Hmvc.find_file(dir, file, ext) – Search each path under dir (e.g. ‘classes’, ‘views’) for file (filename) with the extension (ext, default is “.js”). Hmvc.factory(class_name) – Return a new instance of the given class after loading the corresponding file from the cascading file system. Note that classes should be in the classes subdirectory. Hmvc.load(class_name) – Return whatever require(file-which-contains-the-class) returns. Useful for extending classes, see below for an example.

Please consult a lawyer if you need legal advice.

Copyright 2010 Mikito Takada. All rights reserved.

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Not that I have any official policies.