[jira] [Updated] (GROOVY-10000) Traits should be able to hold constants

["Christopher Smith (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GROOVY-10000?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Christopher Smith updated GROOVY-10000:
---------------------------------------
    Description: 
I can define constants on plain old interfaces; since they're implicitly {{public static final}}, just {{String PREFIX = 'asdf_'}} will get the job done.

However, in a trait, while I can declare a constant and use it within the trait, I can't access that constant from outside the trait. Instead, I get this error (in static mode for better message; dynamic mode generates bytecode demonstrating the same semantic error):

{code:groovy}
trait MyTrait {
  public static final String PREFIX = 'foo'
}
{code}

{code:groovy}
// in another class
doStuff(MyTrait.PREFIX, data)
{code}

{code}
[Static type checking] - No such property: PREFIX for class: java.lang.Class <com.example.MyTrait>
{code}

The compiler seems to be treating what should be a distinct symbol {{MyTrait.PREFIX}} as a property access on the class {{MyTrait}}. I expected the {{PREFIX}} constant to be copied to the generated interface {{.class}} file and available as it would be on an interface. Instead, it appears that it's being put into the {{$Trait$Helper.class}} file. Perhaps the trait AST needs a special rule to recognize constants and route them suitably?

  was:
I can define constants on plain old interfaces; since they're implicitly {{public static final}}, just {{String PREFIX = 'asdf_'}} will get the job done.

However, in a trait, while I can declare a constant and use it within the trait, I can't access that constant from outside the trait. Instead, I get this error (in static mode for better message; dynamic mode generates bytecode demonstrating the same semantic error):

{code:groovy}
doStuff(MyTrait.PREFIX, data)
{code}

{code}
[Static type checking] - No such property: PREFIX for class: java.lang.Class <com.example.MyTrait>
{code}

The compiler seems to be treating what should be a distinct symbol {{MyTrait.PREFIX}} as a property access on the class {{MyTrait}}. I expected the {{PREFIX}} constant to be copied to the generated interface {{.class}} file and available as it would be on an interface. Instead, it appears that it's being put into the {{$Trait$Helper.class}} file. Perhaps the trait AST needs a special rule to recognize constants and route them suitably?


> Traits should be able to hold constants
> ---------------------------------------
>
>                 Key: GROOVY-10000
>                 URL: https://issues.apache.org/jira/browse/GROOVY-10000
>             Project: Groovy
>          Issue Type: Improvement
>          Components: Compiler
>    Affects Versions: 3.0.7
>            Reporter: Christopher Smith
>            Priority: Major
>
> I can define constants on plain old interfaces; since they're implicitly {{public static final}}, just {{String PREFIX = 'asdf_'}} will get the job done.
> However, in a trait, while I can declare a constant and use it within the trait, I can't access that constant from outside the trait. Instead, I get this error (in static mode for better message; dynamic mode generates bytecode demonstrating the same semantic error):
> {code:groovy}
> trait MyTrait {
>   public static final String PREFIX = 'foo'
> }
> {code}
> {code:groovy}
> // in another class
> doStuff(MyTrait.PREFIX, data)
> {code}
> {code}
> [Static type checking] - No such property: PREFIX for class: java.lang.Class <com.example.MyTrait>
> {code}
> The compiler seems to be treating what should be a distinct symbol {{MyTrait.PREFIX}} as a property access on the class {{MyTrait}}. I expected the {{PREFIX}} constant to be copied to the generated interface {{.class}} file and available as it would be on an interface. Instead, it appears that it's being put into the {{$Trait$Helper.class}} file. Perhaps the trait AST needs a special rule to recognize constants and route them suitably?



--
This message was sent by Atlassian Jira
(v8.3.4#803005)