icu4c api proposal: StringEnumeration default implementations

StringEnumeration is an abstract base class (now with a trivial clone() implementation) for 
enumerations that provide a list of strings in C++. Most of the implementations use UnicodeString 
internally, which makes it easy to implement the snext() function which returns a const reference to 
one.

unext() returns a const UChar * and next() returns a const char * - which means that the enumeration 
object requires invariant-character conversion in one direction or another.

I propose to add default implementations for next() and unext() that call snext() and handle the 
conversion, to make it easier to subclass StringEnumeration. With this, there will be a few 
protected helper functions and variables for use by subclasses. There will also be a helper function 
that makes it easier to implement snext() in terms of next().

Expiration: Wednesday, 2003-nov-12

Sincerely,
markus