Holy cow, I wrote a book!
Commenter Anonymous asked
why navigating to a drive with no media displays a dialog
instead of showing the error message in the view.
This is an unfortunate consequence of Explorer's browser/view model.
The shell browser binds to the IShellFolder
and asks for the view by calling
The view window calls
IShellFolder::EnumObjects to figure out what to show
in the view—and here is where the error dialog appears
asking you to insert a disc into the drive.
The problem is that IShellFolder::EnumObjects
has to return an enumerator or an error code.
There is no return value that says "Um, yeah,
could you display this text instead?"
In a narrow sense, there's no way to return it since there is no
way to return a string from IShellFolder::EnumObjects,
but it's also not possible in a broader sense,
since there is no rule that says only shell views can call
Anybody can bind to a shell folder and enumerate its contents.
And most of them don't have any place to display a text message
instead of the enumerated objects.
For example, the folder tree uses IShellFolder::EnumObjects
to fill in children of a node.
If you expand a node for an empty floppy drive,
where is the "Sorry" message supposed to appear?
Now, you might say, "Well, make a special case for Explorer,"
and maybe that's the right thing to do,
but designing in a special case to a general interface
just for one program
tends to create resentment for others:
"How come Explorer can do this but my program can't?"