It's worth mentioning here that SCons maintains a clear distinction between Nodes that represent files and Nodes that represent directories. SCons supports File and Dir functions that, repectively, return a file or directory Node:
hello_c = File('hello.c') Program(hello_c) classes = Dir('classes') Java(classes, 'src')
Normally, you don't need to call File or Dir directly, because calling a builder method automatically treats strings as the names of files or directories, and translates them into the Node objects for you. The File and Dir functions can come in handy in situations where you need to explicitly instruct SCons about the type of Node being passed to a builder or other function, or unambiguously refer to a specific file in a directory tree.
There are also times when you may need to refer to an entry in a file system without knowing in advance whether it's a file or a directory. For those situations, SCons also supports an Entry function, which returns a Node that can represent either a file or a directory.
xyzzy = Entry('xyzzy')
The returned xyzzy Node will be turned into a file or directory Node the first time it is used by a builder method or other function that requires one vs. the other.