What relevance do folders have in a dart project?

Question

When I create a sub folder in a Dart Project in Dart Editor, immediately a package subfolder is created inside this sub folder. I have not read anywhere that sub folders have a special meaning for the project structure, but it appears they do. Anybody knows more?

Answer 1

The package subfolder holds symlinks to your Pub packages. You can read more about Pub and Pub packages at http://pub.dartlang.org/doc/.

When you start a non-web project, the editor will automatically create package directories in your bin/ and test/ directories (but not in your lib/ directory). If you create a web project, a package directory is also created in the web/ folder.

If you add a Pub dependency in the pubspec.yaml file and run pub install, your will see that the package folders will contain symlinks to the Pub package you just installed. If you are using Dart Editor, pub install will automatically run once you modify your pubspec,yaml file.

If you create a subfolder inside any directory that contains one of these auto-generated package folders, the subfolder will get its own package directory. This way, you will have access to your Pub packages no matter how deeply you nest your code in a directory.

Answer 2

Shailen's answer is correct. I wanted to add a bit more, as the title of this question is "What relevance to folders have in a Dart project?"

Dart is designed to be very web friendly. Because there is no load path or classpath on the web, Dart apps must run without requiring an installation or pre-configuration of a local environment.

The only way you can link one file to another in Dart is via a URI. These URIs can be file URIs, and they can be relative. That means file A.dart can point to file B.dart via an absolute or relative path.

So, to answer you question, there is nothing special about a folder layout for Dart applications. The app will run as long as your Dart file can reference its dependencies via the same kind of linking rules that exist on the web (think <a href="" or <link src="").

However, pub (the Dart dependency manager) does make a few assumptions about package and application layout. If certain conventions are followed, pub can manage symlinks for you so that it's easier to reference 3rd party dependencies. Do you need to use pub? Nope, you can manually copy files around or manually manage symlinks. But pub certainly does make it easier to use packages, given the constraints of Dart's design (no load path, no classpath).