Re: Precursor, symmetry of is_equal

Daniel F Moisset schrieb:

[...]
> My problem will also happen in ETL3 if I get it correctly.
> 
> Just to clarify, let me post some code. It crashes at least in SE 2.x.
> If you have other compilers handy (I do not right now), I would like
> to know what the results are:
> 
> deferred class PARENT
> 
[...] -- Is OK
> 
> 
> class CHILD
> 
> inherit
>     PARENT redefine is_equal end

-- Add here the following
      PARENT
        rename is_equal as is_equal_parent
        select is_equal_parent
        end
> 
> create
>     make
> 
> feature
> 
>     make (a_a, a_b, a_c: STRING) is
>         require
>             a_a /= Void
>             a_b /= Void
>             a_c /= Void
>         do
>             a := a_a
>             b := a_b
>             c := a_c
>         end
> 
>     c: STRING
> 
>     is_equal (other: like Current): BOOLEAN is
>         do
-- Precursor is ambiguous at this point, so the following line has to be
-- replaced by
              Result := is_equal_parent (other)
--
-- >             Result := Precursor (other)
>             Result := Result and c.is_equal (other.c)
>         end
> 
> invariant
>     c /= Void
> 
> end
> 
> class MAIN
> 
[...] -- Is OK
> 
With this small change the example compiles end runs with EiffelStudio
5.7.
In fact »equality« as definded in PARENT and in CHILD are different
relations, and both are needed explicitly. So we must inherit two times
from PARENT, and »Precursor« is no more applicable. Do I misunderstand
anything?

Regards
-- 
Gerald Hammer