Smalltalkで列挙型(enum)

予想通りだった。

Enumeration type implementation - Squeak Smalltalk Beginners:

EpcimCurrency class 
   instanceVariableNames: 'enums'

EpcimCurrency class >> validate: aString 
   enums ifNil: [ self initialize ]. 
   ^ enums includesKey: aString.

EpcimCurrency class >>  enums   "for displaying in pulldown menus" 
   enums ifNil: [ self initialize ]. 
   ^enums copy

EpcimCurrency class >> initalize 
   (enums := Dictionary new) 
               add: 'USD'-> 'US dollar' ; 
               add: 'EUR'-> 'European euro' ; 
               add: 'AUD'-> 'Australian dollar' ; 
               add: 'CAD'-> 'Canadian dollar' ; 
               add: 'CHF'-> 'Swiss francs' ; 
               add: 'CNY'-> 'Chinese yuan renminbi' ; 
               add: 'DKK'-> 'Danish crown' ; 
               add: 'GBP'-> 'British pound' ; 
               add: 'JPY'-> 'Japanese yen' ; 
               add: 'NOK'-> 'Norwegian crown' ; 
               add: 'RUR'-> 'Russian ruble' ; 
               add: 'SEK'-> 'Swedish crown' ; 
               add: 'INR'-> 'India rupees' ; 
               add: 'other'-> 'Another type of currency' .