Re: agents / TUPLE inheritance

Peter Gummer wrote:

> Hi Raphael,
>
> I think you may have encountered a consequence of a difference of 
> opinion described in this paper by Philippe Ribet:
>
> http://www.jot.fm/issues/issue_2004_04/article7
>
> I use the ISE compiler, and on several occasions I have encountered 
> the problem that the article seeks to fix. For this reason, I have 
> tended to agree with the SmartEiffel approach to agent conformance.
>
Thanks for your support Peter!
Raphael, you should really read the paper to know more about this problem.

> Your problem is interesting, though. It seems to demonstrate that the 
> ISE/ECMA approach also has advantages.
>
>
 From my point of view, this example gives nothing in favour of ISE/ECMA 
approach. In few simple words:
a: ROUTINE[ANY, TUPLE[TT]]  ---> "a" is a routine able to handle 
arguments of type TT.

"g" is declared as "g(i: T1) is", so it is not able to handle arguments 
of type TT. That's why the compiler refuses to assign "agent g" into "a".

Is this clear enough?

Best regards

>
> On 08/04/2005, at 3:58 AM, Raphael Mack wrote:
>
>> Hi,
>>
>> I tired to compile the following code:
>>
>> class A
>>
>> creation
>>     make
>>
>> feature
>>     make is
>>         local
>>             t: T1
>>         do
>>             create {T1}t
>>             a := agent g(?)
>>             a.call([t])
>>         end
>>
>>     g(i: T1) is
>>         do
>>             io.put_string(i.out)
>>         end
>>
>>     a: ROUTINE[ANY, TUPLE[TT]]
>>
>> end
>>
>>
>> with T1 and TT:
>> class TT
>> end
>>
>>
>> class T1
>> inherit TT
>>         redefine
>>                 out
>>         end
>> creation
>>         default_create
>> feature
>>         out: STRING is
>>                 do
>>                         Result := "T1..."
>>                 end
>> end
>>
>> And I get
>> ****** Fatal Error:  Bad assignment (VJAR). Cannot assign `agent
>> g(?)' which is of type PROCEDURE[ANY,TUPLE[T1]] into `a' which
>> is of type ROUTINE[ANY,TUPLE[TT]].
>> Line 12 columns 4, 9 in A (/home/r/eiffel/se_test/a.e):
>>          a := agent g(?)
>>          ^    ^
>> ------
>>
>> For me, this seems to be perfectly fine Eiffel (and it works with 
>> ise) - what's wrong with it?
>>
>> Thanks,
>> Raphael
>>
>
>
>


-- 
Philippe Ribet



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