Seven Low-Cost Ways to Improve Legacy Code
Subject:   Enums and "Constant Object"
Date:   2004-10-28 08:53:34
From:   dubwai
Response to: Enums and "Constant Object"

"As for the term "type-safe-enum" I personally think that would cause confusion since the code is not exactly declaring an enum (which has other semantics as well) but merely several objects that cannot be changed (IE constant)."

My mistake. The term is 'type-safe enumeration'. I call it a typesafe enum as an abbreviatioon and becasue there are no 'enums' in pre 1.5 Java (and arguably even in 1.5.)

"There is no convention that says that only integral and string and other primitive types are the only kinds of things that are constant."

String isn't a primitive type. Really what you are talking about are 'literals'. There are no constants in Java. We call static finals 'constants' because they work like them. If the 'const' keyword is ever introduced into Java (unlikely, I think) this will really be confusing.

"A constant is simply something that can not be changed; the antithesis of variable."

Well, not exactly but in any event using the term constant confuses developers because it implies that marking a reference constant makes the Object it references unchangeable. I can't even count how many times I've seen people confused about why Strings are Objects but act like primitives.

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  • Enums and "Constant Object"
    2004-10-28 09:20:11  Robert Simmons, Jr. | O'Reilly Author [View]

    "In programming, a constant is a value that never changes. The other type of values that programs use is variables, symbols that can represent different values throughout the course of a program."[1]

    Since these objects are alocated at initialization and never change, they are constants.

    As for the terms for them, its a matter of splitting of irrelevant hairs. The importance is in the concept, not the label. Call them Freds for all I care.


    • Enums and "Constant Object"
      2004-10-28 09:30:40  dubwai [View]

      "As for the terms for them, its a matter of splitting of irrelevant hairs. The importance is in the concept, not the label. Call them Freds for all I care."

      That's fine for casual conversation but I don't think it's OK for technical books or articles.

      I have a book that describes certain well-known patterns improperly. The pattern described is useful but the name is normally assigned to something else entirely. This isn't just splittuing hairs. It puts the reader at a disadvantage when conversing with others. It's hard to communicate when people don't agree on the definitions of words.
      • Enums and "Constant Object"
        2004-10-28 10:02:27  Robert Simmons, Jr. | O'Reilly Author [View]

        Fine then. Id advise you to write your own articles if you feel your technical competence is so high and mine so low. You may find that its not as easy as you might think.

        Im having nothing more to do with this pointless conversation.
        • Enums and "Constant Object"
          2004-10-28 13:41:07  dubwai [View]

          A little defensive, there.

          I've never really understood that argument. If some one paints your portrait and it doesn't meet your expectations, are you not allowed to criticize the work unless you can do better?

          I may write a book some day. I don't think I'm really quite qualified to do so. I'll just leave it at that.