Re: [aspectj-users] Just for fun: declare error to prevent use of inheri

[Matthew Adams <matthew@xxxxxxxxxxxxxxx>]

A bit terser, now:

public aspect Extend {

  public static class Nothing {}

  declare parents :
    !Enum+ &&
    !Annotation+ &&
    whatever..* // classes to restrict
    extends Nothing;
}

:)

On Fri, Aug 17, 2012 at 3:33 PM, Matthew Adams <matthew@xxxxxxxxxxxxxxx> wrote:
> ...and here you go:
>
> public aspect DontExtend {
>
>   public static class Anything {}
>
>   declare parents :
>     !Enum+ &&
>     !Annotation+ &&
>     whatever..* // classes to restrict
>     extends Anything;
> }
>
> This yields the following compilation error for me:
>
> [ERROR] Failed to execute goal
> org.codehaus.mojo:aspectj-maven-plugin:1.4:compile (default) on
> project app-domain: Compiler errors:
> [ERROR] error at declare parents :
> [ERROR] !Enum+ &&
> [ERROR] !Annotation+ &&
> [ERROR] app.domain.model..*
> [ERROR] extends Anything;
> [ERROR] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> [ERROR] /Users/matthew/Documents/test/production/app/domain/src/main/aspect/app/domain/aspect/horizontal/DontExtend.aj:12:0::0
> can only insert a class into hierarchy, but
> app.domain.aspect.horizontal.DontExtend$Anything is not a subtype of
> app.domain.model.Test
>
> Works!
>
> I was thinking also about how to force all model classes to be final.
> I thought about some form of either 'declare error : !final
> app.domain.model..* : "model classes must be final"' or an ITD to
> introduce the final modifier.  Is that possible?
>
> -matthew
>
> On Fri, Aug 17, 2012 at 12:45 PM, Matthew Adams <matthew@xxxxxxxxxxxxxxx> wrote:
>>
>> Interesting.  I like all of the suggestions.  I entered an issue to track this:
>> https://bugs.eclipse.org/bugs/show_bug.cgi?id=387499
>>
>> Thanks!
>>
>>
>> On Thu, Aug 16, 2012 at 3:05 PM, Andy Clement <andrew.clement@xxxxxxxxx> wrote:
>>>
>>> I haven't spent toooo long thinking about it, but I don't think you
>>> can at the moment. We don't really have the capabilities to introspect
>>> the class hierarchy to that level of detail.
>>>
>>> Some made up syntaxes:
>>>
>>> If 'Object+' indicates subtypes, let's add a numeric to indicate distance:
>>> declare error:  within(Object+2): "Type does not directly extend
>>> object"; // maybe add the type category type pattern too:
>>> within(is(ClassType) && Object+2)
>>> declare error: within(Object+>2):   "Type does not directly extend object";
>>>
>>> More direct:
>>> declare error within(!extends(Object)): "Type does not directly extend
>>> object"; // if 'extends' is strictly looking at the declared type and
>>> not the inheritance chain.
>>>
>>> You could probably cause an error if you tried to use declare parents
>>> extends with a simple type because extends will report an error if the
>>> new type doesn't have the same parent as the existing type:
>>>
>>> class Foo1 {}
>>> class Foo2 extends ArrayList {}
>>>
>>> class Marker {}
>>>
>>> aspect X {
>>>   declare parents: Foo* extends Marker;
>>> }
>>>
>>> will give an error ... but it isn't as simple as a nice message saying
>>> 'type Foo2 doesn't directly extend Object.'
>>>
>>> cheers,
>>> Andy
>>>
>>> On 16 August 2012 08:40, Matthew Adams <matthew@xxxxxxxxxxxxxxx> wrote:
>>> > Just for fun, I was trying to think of how to use declare error to prevent
>>> > the use of class inheritance in user code, but I can't think of how to do
>>> > that.
>>> >
>>> > Basically, if you wanted to disallow the declaration of classes that extend
>>> > anything other than Object, is there a "declare error" form that would work?
>>> >
>>> > -matthew
>>> >
>>> > --
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>>> > skype:matthewadams12
>>> > googletalk:matthew@xxxxxxxxxxxxxxx
>>> > http://matthewadams.me
>>> > http://www.linkedin.com/in/matthewadams
>>> >
>>> >
>>> > _______________________________________________
>>> > aspectj-users mailing list
>>> > aspectj-users@xxxxxxxxxxx
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>>> >
>>> _______________________________________________
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>>
>>
>>
>>
>> --
>> mailto:matthew@xxxxxxxxxxxxxxx
>> skype:matthewadams12
>> googletalk:matthew@xxxxxxxxxxxxxxx
>> http://matthewadams.me
>> http://www.linkedin.com/in/matthewadams
>>
>
>
>
> --
> mailto:matthew@xxxxxxxxxxxxxxx
> skype:matthewadams12
> googletalk:matthew@xxxxxxxxxxxxxxx
> http://matthewadams.me
> http://www.linkedin.com/in/matthewadams



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