groovy

Add support for implementing a Java interface with methodMissing

Details

  • Type: New Feature New Feature
  • Status: Open Open
  • Priority: Major Major
  • Resolution: Unresolved
  • Affects Version/s: None
  • Fix Version/s: 1.8.x, 2.x
  • Component/s: None
  • Labels:
    None
  • Number of attachments :
    1

Description

We should make it possible to implement any Java interface with method missing:

class Foo {
    def methodMissing(String name, args) { null }
}

def f = new Foo()
def ctx = f as SomeInterface

The proxy would simply delegate from the interface through methodMissing

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Andres Almiray added a comment -

What is the rationale for this feature?

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Andres Almiray added a comment - What is the rationale for this feature?
Guillaume Laforge made changes -
Field Original Value New Value
Fix Version/s 1.7-beta-1 [ 14014 ]
Fix Version/s 1.7-beta-x [ 15538 ]
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Steve Ardis added a comment - - edited

My scenario is this. I'm using Grails 1.2-M3, which depends on Groovy 1.6.4. I'm also using the Grails Remoting Plugin, which requires an interface.

What I would like to be able to do is create methods on an interface, parse them in methodmissing(..) and in-turn invoke the appropriate method on the GORM object.

For example:

UserServiceIF.java:

 
interface UserServiceIF { User findUserByUsername(String username); }

UserService.groovy:

 
@Mixin(DAOMixin)
class UserService implements UserServiceIF {
}

DAOMixin.groovy:

 
class DAOMixin {
    def methodMissing(String name, args) {
        ...
        // parse GORM object name and method
        // return User.findByUsername(username)
    }
}

I've dumbed this scenario down to the attached file - GroovyInterfaceTests.groovy – NOTE!! You have to uncomment the c() and d() methods from the interface to get the compilation error.

I know there was a JIRA issue to fix this already for @Delegate in Groovy 1.6.4 - its functionality is verified in the provided test case.

My belief is that no Groovy class should ever have an issue with "Can't have an abstract method in a non-abstract class." during compilation. Instead, the Groovy compiler should check for methods provided through any @Delegate or @Mixin; if methods are still missing on the class, the compiler should dynamically create the method on the class and invoke methodmissing(..).

I'll admit I have no background with writing compilers and have no knowledge to the feasibility of this - it just feels like it should be able to happen.

Thanks -
Steve Ardis

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Steve Ardis added a comment - - edited My scenario is this. I'm using Grails 1.2-M3, which depends on Groovy 1.6.4. I'm also using the Grails Remoting Plugin, which requires an interface. What I would like to be able to do is create methods on an interface, parse them in methodmissing(..) and in-turn invoke the appropriate method on the GORM object. For example: UserServiceIF.java: interface UserServiceIF { User findUserByUsername(String username); } UserService.groovy: @Mixin(DAOMixin) class UserService implements UserServiceIF { } DAOMixin.groovy: class DAOMixin { def methodMissing(String name, args) { ... // parse GORM object name and method // return User.findByUsername(username) } } I've dumbed this scenario down to the attached file - GroovyInterfaceTests.groovy – NOTE!! You have to uncomment the c() and d() methods from the interface to get the compilation error. I know there was a JIRA issue to fix this already for @Delegate in Groovy 1.6.4 - its functionality is verified in the provided test case. My belief is that no Groovy class should ever have an issue with "Can't have an abstract method in a non-abstract class." during compilation. Instead, the Groovy compiler should check for methods provided through any @Delegate or @Mixin; if methods are still missing on the class, the compiler should dynamically create the method on the class and invoke methodmissing(..). I'll admit I have no background with writing compilers and have no knowledge to the feasibility of this - it just feels like it should be able to happen. Thanks - Steve Ardis
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Steve Ardis added a comment -

GroovyInterfaceTests added (see comment by Steve Ardis on 10/23/2009 for reference).

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Steve Ardis added a comment - GroovyInterfaceTests added (see comment by Steve Ardis on 10/23/2009 for reference).
Steve Ardis made changes -
Attachment GroovyInterfaceTests.groovy [ 45423 ]
blackdrag blackdrag made changes -
Fix Version/s 1.8.x [ 15750 ]
Fix Version/s 2.x [ 17013 ]
Fix Version/s 1.7.x [ 15538 ]

People

  • Assignee:
    Unassigned
    Reporter:
    Graeme Rocher
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  • Created:
    Updated: