Selecting a project from the command line

[Manuel Gómez]

I've playing with Alire and configured the edit command to use emacs but 
the simplest approach is only opening the file:

$ alr config editor.cmd
editor.cmd=emacs ${GPR_FILE}

Is there a way from the command line to load that GPR file?
I've tried some variations of this which have all failed:

emacs --eval '(progn (require '\''ada-mode) (ada-build-default-prj 
'\''project.gpr))'