[aspectc-user] run-time aspects

[Jamal Siadat]

Hi,
Yes, nesting classes within aspect would greatly help. However I do seem
to have issues when I'm trying to create actual class objects for
instance:

int main (){
       B n;
  return 0;
}

A.h:
class A{
 public:
int a;
};


aspect :

#include "A.h"
using namespace std;
aspect asp  {
class B: public A {
int m ;
};
};


When I try to compile the main file using the aspect I get:
A.cc:6: error: invalid statement near token `n'
So for reason I can't create instances of B. Is there any way to introduce
B somehow using an aspect? and be able to create instances of it?

Thanks,
Jamal

> Hi,
>
> once again I'm not sure what you want to achieve :-(. It sounds as if
> nested classes might help you. For example, you can declare a class in a
> class or a class in an aspect:
>
> aspect Foo {
>   class Nested : public A {
>      ...
>   };
> };
>
> - Olaf
>
> Jamal Siadat wrote:
>>Hi,
>>yes that helped to a great extent, but is there any way to "introduce" a
>>class which is a sub-class of another inside an aspect? In our example
>> can
>>I create B inside an aspect say:
>>
>>Aspect B : public A {
>>
>>// the rest of  is defined here
>>};
>>
>>or alternatively:
>>
>>Aspect extend : public A {
>>// create new class B in here which will be a sub-class of A?
>>};
>>
>>Is any of those two methods possible and will it result in me being able
>>to instantiate objects of type B?
>>
>>Thanks,
>>
>>
>>
>>>Hi,
>>>
>>>the new members of A that are introduced by B and C become ordinary
>>>members after weaving the aspects. There are neither base classes nor
>>>derived classes generated. However, you could do something like this:
>>>
>>>class B {
>>>   int y;
>>>};
>>>
>>>aspect B_in_A {
>>>public:
>>>   advice "A" : baseclass (B);
>>>};
>>>
>>>This will make the "class B" a public base class of A. You could then
>>>instantiate B objects without the rest of A.
>>>
>>>Alternatively, you could also derive the classes B and C from A. It
>>>sounds as if this is what you want. However, you don't need any aspect
>>>for this. If B and C use virtual inheritance, you could even create a
>>>class that inherits from B and C that contains only one instance of A.
>>>Of course, you could introduce the base class relationship between B and
>>>A as well as C and A by baseclass introduction as shown above.
>>>
>>>Does that help?
>>>
>>>Olaf
>>>
>>>
>>>Jamal Siadat wrote:
>>>
>>>>Hi,
>>>>Here is the second part:
>>>>if so when I am running the
>>>>
>>>>>>program
>>>>>>can I have:
>>>>>>B b;
>>>>>>b.y=5;
>>>>>>If not, what alternatives would I have so I can just create B type
>>>>>> at
>>>>>>run-time like above?
>>>>>>
>>>>Which means I would like to create and access objects "B" or objects of
>>>>"C" since I assume B and C will be created as sub-classes of A when
>>>>compiled. If not What other alternatives do I have to compile two
>>>>aspects
>>>>to extend a class and then create objects of each ?
>>>>
>>>>Thanks,
>>>>
>>>>
>>>>
>>>>
>>>>>Hi,
>>>>>
>>>>>first of all, there are a few syntax errors in your code. For
>>>>> instance,
>>>>>aspect B should look like this:
>>>>>
>>>>>aspect B {
>>>>>  pointcut add() = "A";
>>>>>  advice add() : int y;
>>>>>};
>>>>>
>>>>>Besides this syntax problem, you could compile both aspects together
>>>>>with your component code. The weaver will introduce the new members
>>>>> "y"
>>>>>*and* "Q" into the class "A".
>>>>>
>>>>>Introductions are a means to implement *static* crosscutting.
>>>>> Therefore,
>>>>>all instances of A will contain both new members.
>>>>>
>>>>>I'm sorry, but I don't understand the second part of your question:
>>>>> "If
>>>>>the answer to the first part is yes Then is there any way create
>>>>> objects
>>>>>of A, B or C independently?". Could you try to explain it again or is
>>>>> my
>>>>>answer already sufficient?
>>>>>
>>>>>- Olaf
>>>>>
>>>>>
>>>>>Jamal Siadat wrote:
>>>>>
>>>>>>Hi All,
>>>>>>I just have a couple of questions I was wondering if you may address
>>>>>>for
>>>>>>me please:
>>>>>>first Does AspectC++ suopport the expansion of a particular class by
>>>>>>two
>>>>>>different aspects that may be compiled simuntaniously?
>>>>>>for instance is it possible to have a class "A" and use aspects "B"
>>>>>> and
>>>>>>"C" to add some methods/variables to it. ( each of A and B add
>>>>>>different
>>>>>>methods and variables).
>>>>>>
>>>>>>If the answer to the first part is yes Then is there any way create
>>>>>>objects of A, B or C independently? Here is an example:
>>>>>>
>>>>>>class A{
>>>>>>A();
>>>>>>~A();
>>>>>>int a;
>>>>>>void b();
>>>>>>}
>>>>>>
>>>>>>aspect B {
>>>>>>pointcut add() : "A";
>>>>>>add (): int y;
>>>>>>//adding integer y to class A
>>>>>>};
>>>>>>
>>>>>>aspect C {
>>>>>>pointcut addition() : "A";
>>>>>>addition (): bool Q;
>>>>>>//adding bolean Q to class A
>>>>>>};
>>>>>>
>>>>>>Can I compile B and C simuntaniously? if so when I am running the
>>>>>>program
>>>>>>can I have:
>>>>>>B b;
>>>>>>b.y=5;
>>>>>>If not, what alternatives would I have so I can just create B type
>>>>>> at
>>>>>>run-time like above?
>>>>>>
>>>>>>Thanks all,
>>>>>>Jamal
>>>>>>
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>>>>>>
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>>
>>
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