Please rethink extended enums inclusion

[Henri Gerrits]

Hi Jose Antonio,
 
I have some issues with your proposal:
 
1. Inserting a superclass with new methods might break many existing enums
2. Why do you need a code field? The name() method already returns a unique value.  The static valueOf() method can then be used instead of your fromCode() method.  I don't think caching makes much sense with enums, since the number of possible values are usually fairly small
3. Although the in(T...) method does look nice at the call site, I think it has nothing to do with the enum; it belongs to a collection class (as "contains()", which admittedly means you need to have a collection instance at the call site)
4. You could also implement the in(T...) method by "mixing in" a (generic) interface using an extension method
 
Best regards,
 
Henri

From: Jose Antonio Illescas Del Olmo <jantonio.illescas at rbcdexia-is.es>
>To: coin-dev at openjdk.java.net
>Sent: Friday, October 7, 2011 7:34 AM
>Subject: Please rethink extended enums inclusion
>
>Now we have hundred of enums on our project (finantial application with 
>120.000 lines) an repeat same code on any enum... (*mark as red*)
>
>
>* Map our enums with old legacy system codes:
>
>    public enum Type {
>
>      ONE("01), TWO("03"), THREE("03"), ...;
>
>      private Type(String code) {
>          setCode(code);
>      }
>
>*      private String code;
>*
>*    public String code() {
>          return code;
>      }
>
>      public void setCode(String code) {
>          this.code = code;
>      }
>
>**      public static Type fromCode(String code) {
>          if (code == null) return null;
>          for(Type type: values()) {
>              if (type.code.equals(code) return type;
>          }
>          return null;
>      }
>
>**      public boolean in(Type... types) {  // IMO all enums must have 
>this method
>          if (types == null) return false;
>          for(Type type: types) {
>              if (this == type) return true;
>          }
>          return false;
>      }
>*
>Or with cache to avoid for iteration on fromCode(String) method => more 
>code is necesary
>
>public enum Type {
>
>      ONE("01), TWO("03"), THREE("03"), ...;
>
>      private Type(String code) {
>          setCode(code);
>      }
>
>*      private String code;
>
>**      private static Map<String, Type> cache= new HashMap<String,Type>();
>
>      static {
>          for(Type type: Type.values()) {
>              cache.put(type.code(), type);
>          }
>      }
>*
>*    public String code() {
>          return code;
>      }
>
>      public void setCode(String code) {
>          this.code = code;
>      }
>
>**      public static Type fromCode(String code) {
>          return cache.get(code);
>      }
>
>**      public boolean in(Type... types) {  // IMO all enums must have 
>this method
>          if (types == null) return false;
>          for(Type type: types) {
>              if (this == type) return true;
>          }
>          return false;
>      }*
>
>/Abstract enums with Generic support reduce dramatically the code of 
>enums, see next code that use abstract enums:
>/
>*public enum Type extends MyAbstractEnum<String> {
>
>      ONE("01), TWO("03"), THREE("03"), ...;
>
>      private Type(String code) {
>          super(code);
>      }
>  }*
>
>
>
>
>