[Chandler-dev] a new kind of enumeration type

[Andi Vajda]

On Wed, 30 Aug 2006, Phillip J. Eby wrote:

> We could do that, after we got rid of any existing code that depends on the 
> old semantics of enumerations.

I could rename the old enumeration to StringEnumeration and introduce a new 
enum that behaves like what Grant is suggesting.

> However, it should be noted that this may lead to interesting problems in 
> schema upgrades.  My understanding is that the reason for wanting explicit 
> values (as opposed to simple sequence) is that it allows constant values to 
> be preserved across releases, even if things are added or removed.  Second, 
> it allows the use of enumerations as constants for interacting with external 
> systems, like socket mode flags and such.

I should dispell any rumors of constant-ness across schema changes. The value 
that gets persisted for a new type of enum value is the position of the 
constant in the sorted-by-constant-name constant list. If someone renames a 
constant or inserts one alphabetically, that's a schema change.

Andi..