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enum syntax

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  enum syntax ruben safir <ruben@mrbrklyn.com> - 2016-05-07 23:58 -0400
    Re: enum syntax Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2016-05-07 21:43 -0700
      Re: enum syntax Roedy Green <inquiry@mindprod.com> - 2016-07-12 04:35 -0700
    Re: enum syntax Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-08 07:22 -0400
    Re: enum syntax Roedy Green <see_website@mindprod.com.invalid> - 2016-05-20 18:01 -0700

#34260 — enum syntax

How is there no closing paran and a method included as an enum entry?

what is this syntax ?


/**
 * An enumeration representing all base types in Calc. It also includes
 * the ERROR designation, used by the type checker to propagate errors.
 */
public enum Type {
    INT,
    FLOAT,
    BOOL,
    STRING,
    ERROR;

    /**
     * The types form a hierarchy, with ERROR at the root.
     * @return The least upper bound of this and that.
     */
    public Type leastUpperBound(Type that) {
        if(this == that)
            return this;
        if((this == INT && that == FLOAT)
            ||(this == FLOAT && that == INT))
            return FLOAT;
        return ERROR;
    }

    /**
     * Determines whether the type is numeric, defined as INT or FLOAT.
     */
    public boolean isNumeric() {
        return leastUpperBound(FLOAT) == FLOAT;
    }
}
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#34261

On 5/7/2016 20:58, ruben safir wrote:
> How is there no closing paran and a method included as an enum entry?
>
> what is this syntax ?
>
>
> /**
>  * An enumeration representing all base types in Calc. It also includes
>  * the ERROR designation, used by the type checker to propagate errors.
>  */
> public enum Type {
>     INT,
>     FLOAT,
>     BOOL,
>     STRING,
>     ERROR;
>
>     /**
>      * The types form a hierarchy, with ERROR at the root.
>      * @return The least upper bound of this and that.
>      */
>     public Type leastUpperBound(Type that) {
>         if(this == that)
>             return this;
>         if((this == INT && that == FLOAT)
>             ||(this == FLOAT && that == INT))
>             return FLOAT;
>         return ERROR;
>     }
>
>     /**
>      * Determines whether the type is numeric, defined as INT or FLOAT.
>      */
>     public boolean isNumeric() {
>         return leastUpperBound(FLOAT) == FLOAT;
>     }
> }
>

 From the JLS "In  addition  to  enum  constants,  the  body  of  an 
enum  declaration  may  contain
constructor and member declarations as well as instance and static 
initializers."  See JLS 8.9.2.


-- 

Knute Johnson

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#34868

On Sat, 7 May 2016 21:43:54 -0700, Knute Johnson
<nospam@rabbitbrush.frazmtn.com> wrote:

>> How is there no closing paran and a method included as an enum entry?

I don't see a method attached to an enun constant, though it is a
techquique I use all the time.

for instance in an enum of bookstores, I have a method  to compose a
probe to that store.  It overrides an abstract method common to all
enums.  If I say bookstore.probe() is selects the correct version.

I don't see any () or {} unbalanced.  I am notoriously bad at
proofreading them. Where are they?

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#34263

On 5/7/2016 11:58 PM, ruben safir wrote:
> How is there no closing paran and a method included as an enum entry?
>
> what is this syntax ?

     There's a good explanation at

http://docs.oracle.com/javase/tutorial/java/javaOO/enum.html

Read it, then post again if you still have questions.

-- 
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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#34360

On Sat, 7 May 2016 23:58:42 -0400, ruben safir <ruben@mrbrklyn.com>
wrote, quoted or indirectly quoted someone who said :

>       if(this == that)
>            return this;
>        if((this == INT && that == FLOAT)
>            ||(this == FLOAT && that == INT))
>            return FLOAT;

this is does more tersely with a SWITCH.
-- 
Roedy Green Canadian Mind Products http://mindprod.com
Incorrect documentation is often worse than no documentation.
~ Bertrand Meyer (born:1950 age 65)

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