Multiple versions of alpha on your local drive
Many users have several different copies of Alpha on your local drive, i.e. version 7.5 and 7.6. Or they might have two copies of AlphaX -- one that has the CURRENT version of AlphaTcl and another that has the HEAD version that they updated via the CVS.AlphaTclCVS.
Users with multiple versions of Alpha might the following information useful. Topics include:
All versions of Alpha create a preferences folder somewhere in your local drive. This folder contains configuration information and package indices that are compiled from information in your local AlphaTcl library, which (after it has been created) makes startup sequences much faster. All of your edited preferences are also stored in preference folder files with names like arrDefs.tcl and are saved between editing sessions.
Why should you care about Alpha's preferences folder? If you have two different versions of Alpha lying about, chances are that they are going to use slightly different Cache information, especially with regard to version numbers of the AlphaTcl library. In general, two different versions cannot and should not share the same prefs folder, and when switch back and forth between the applications you might discover that you are told that 'Package Indices need to be rebuilt' whenever you start Alpha.
Default Prefs Folder Locations
See the WhereIsMyAlphaPreferencesFolder wiki page for the default location.
User-Defined Prefs Folder Location
If you create a folder named AlphaPrefs and place it at the same level of the Alpha application, i.e.
/Applications/Alpha/AlphaPrefs /Applications/Alpha/AlphaX.app /Applications/Alpha/Examples /Applications/Alpha/Help /Applications/Alpha/Tcl /Applications/Alpha/Tools
this folder will be used preferentially. This will allow you to maintain two or more separate versions of Alpha without rebuilding indices each time that you switch back and forth amongst them.
/Applications/Alpha 8.1/AlphaPrefs /Applications/Alpha 8.1/AlphaX.app /Applications/Alpha 8.1/Examples ... /Applications/Alpha 8.0/AlphaPrefs /Applications/Alpha 8.0/AlphaX.app /Applications/Alpha 8.0/Examples ...
Note that if you maintain multiple AlphaPrefs folders, saved preferences will not be shared amongst your Alpha applications.
Identifying the current Prefs Folder location
Alpha maintains a variable named $PREFS that stores the current path of the preference folder used by the open application. You can enter the following command in the status bar command line (press Escape-X) or in an AlphaTcl Shell window (select Utils > Tcl Shell)
to display this folder in the OS Finder. (There is a similar [$HOME] variable that stores the path of the folder containing the application.)
Which application / version gets used?
If you have multiple versions of Alpha installed on your local drive, there is no way for us (as users, as developers) to know which one is going to be selected by the Finder when you double click on an Alpha file. In this case, you're always better off starting the application first, or (if you want to keep the other versions around but don't really use them) you can use DropStuff or some other compression utility to archive all copies of the Alpha application except for the one that you primarily use.