Why can't I use .app bundles symlinked into /Applications as default in the 'open with' dialog?

I have installed emacs with homebrew, with the --cocoa flag, which makes homebrew create an .app bundle in /usr/local/Cellar/emacs/<version>/Emacs.app. I have symlinked the .app bundle into /Applications/, to make it easy to open. The problem is that when I try setting file associations for files, I can't set Emacs.app as the default (the Add button is greyed out):

Now I could just copy or move the .app bundle into /Applications/, but that would require me to copy it over again every time emacs is updated via homebrew. Is there some other way to solve this?

I don't know why, but I have figured it out that if I make the symlink to the Contents directory, then associations work fine.

That is I do the following in a terminal window, using my personal Applications folder as an example:

% mkdir ~/Applications/Emacs.app
% ln -s /usr/local/Cellar/emacs/23.2/Emacs.app/Contents ~/Applications/Emacs.app

Something about putting the symlink inside the Emacs.app gets the bundle recognized.

Weird. I just installed emacs through brew and it automatically updated the "open with" dialog to include Emacs.app ; But you should be able to do the following: Directly after opening the "choose an application" dialog, press "/" to get a "go to folder" window. Enter the following path:

/usr/local/Cellar/emacs/

and from there navigate to the Emacs.app (at the current version this should be /usr/local/Cellar/emacs/23.2/Emacs.app) and select it as default application.

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Could you please run the following command to see whether Emacs is registered in your LaunchServices DB?

/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -dump | grep Emacs

If it's not something you do often, you can navigate to the place where Emacs.app is really and assign it from there.

Did you try to change the "Enable: Recommended Applications" dropdown? I believe there's a "All applications" option. Maybe this one will let you select your alias.

You said you symlinked the .app. Did you use ln -s? If so, did you try using an alias instead?

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I don't know homebrew very well, but it look like you can extend homebrew with external commands.

Try to look if you can get the updated .app file and cp to /Applications.