The class inherits two different generic derivations of the same class

Question

What is the proper way of precising the type of an iterable through inheritence.

as inherit FOO[like babar] is not alowed

FOO

class FOO

inherit
    ITERABLE[detachable ANY] -- I know garbage but for DB_RESULT its the case


feature -- Access

    new_cursor: ITERATION_CURSOR[like items.item]
        do
            Result := items.new_cursor
        end

    items: ARRAY[detachable ANY]


end -- class FOO

BAR

class BAR

inherit
    FOO -- I know garbage but for DB_RESULT its the case

    ITERABLE[STRING] -- I know garbage but for DB_RESULT its the case


feature -- Access

    new_cursor: ITERATION_CURSOR[like items.item]
        do
            Result := items.new_cursor
        end

    items: ARRAY[STRING]


end -- class FOO

score 1 · Accepted Answer · answered Jun 12 '20 at 19:36

1

I would suggest using a formal generic parameter in class FOO:

class FOO [G]
inherit
    ITERABLE [G]

Then, class BAR would provide a suitable actual generic parameter:

class BAR
inherit
    FOO [STRING]

answered Jun 12 '20 at 19:36

Alexander Kogtenkov

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I was thinking too about this solution, but don't want to give for each l_foo: FOO[detachable ANY] but maybe the only way is to 'FOO_GENERIC_ANY inherit FOO[detachable ANY]' :( – Pipo Jun 12 '20 at 19:39
1

@Pipo As far as I know, anchored types are not going to be supported in parent clauses soon, so I do not see a better solution at the moment. – Alexander Kogtenkov Jun 12 '20 at 19:47

The class inherits two different generic derivations of the same class

FOO

BAR

1 Answers1