[5283] in java-interest
Re: [Q] (Promblematic) Lack of enum in Java
daemon@ATHENA.MIT.EDU (Greg Ewing)
Mon Feb 5 07:29:32 1996
Date: Mon, 5 Feb 1996 16:06:09 +1100
From: grege@optimation.com.au (Greg Ewing)
To: java-interest@java.sun.com
> From NewsGroup_comp-lang-java Sun Feb 4 10:09 EST 1996
> From: NewsGroup_comp-lang-java
> >From: tmb@best.com--Internet
> Subject: Re: [Q] (Promblematic) Lack of enum in Java
> Date: 03 Feb 1996 02:54:41 -0800
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Fellow javans,
Why not do something like this if you want enum-like constants:
class ParseStatus {
public static final ParseStatus STATEA = new ParseStatus();
public static final ParseStatus STATEB = new ParseStatus();
public static final ParseStatus STATEC = new ParseStatus();
}
You can then use it like this:
class StatusDemo {
private ParseStatus status;
public void setStatus(ParseStatus newStatus) {
status = newStatus;
}
public ParseStatus getStatus() {
return status;
}
public boolean isStateA() {
return (status == ParseStatus.STATEA);
}
public boolean isStateB() {
return (status == ParseStatus.STATEB);
}
}
then:
StatusDemo foo = new StatusDemo;
foo.setStatus(ParseStatus.STATEA);
if (foo.isStateA) do something;
GREG
grege@optimation.com.au
> In article <SAMURAI.96Feb2110932@random.hasc.ca> samurai@random.hasc.ca (Darcy Brockbank) writes:
> | > class ParseStatus {
> |
> | > public static final int STATEA = 1;
> | > public static final int STATEB = 2;
> | > public static final int STATEC = 3;
> |
> | > }
> |
> |
> | This is one place where Java drops the ball. Syntactically, you are
> | simply defining constants, just as you would do with #define or
> | enum. [...]
> |
> | They should either remove ints, and switches from the language entirely,
> | and consider everything as objects, or have proper mechanisms for
> | dealing with them. [...]
> | I'm back to writing a bunch of switch statements, and
> | the compiler now has no ability to check me for omissions. And, anyone
> | using my code has to scan it very carefully to see which integer tags I
> | might be returning... rather than having the program stand up and shout
> | it at them.
>
> What you really want is a construct for tagged and statically checked
> type unions. I believe the Espresso folks are adding this to their
> extension of Java based on what SML provides. This is something that
> has been sorely missing in many OOLs.
>
> Thomas.
>
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