Re: Liberty-eiffel Digest, Vol 53, Issue 9

[Paolo Redaelli]

Il 21/02/22 00:10, Eric Bezault ha scritto:
> On 20/02/2022 23:39, Paolo Redaelli wrote:
> > Wise words. I always wondered if "inherit {NONE}" is non conforming 
> > inheritance, what's the meaning of "inherit {ANY}" or inherit 
> > "{SOME_OTHER_CLASS}" ?
>
> * inherit {NONE}: inheritance link (i.e. conformance) visible
>   by no class. No client knows that the current class inherits
>   from its parent, and therefore we cannot use this property
>   when trying to figure out whether the type of the source of an
>   assignment appearing in the client class conforms to the type
>   of the target.
>
> * inherit {ANY}: inheritance link visible by all classes.
>
> * inherit {SOME_OTHER_CLASS}: inheritance link visible only
>   by descendants of class SOME_OTHER_CLASS.
>
>
> It's not very different from the notions 'feature {FOO}' or
> 'create {FOO}' where the feature or creation procedure is visible
> only to descendants of class FOO, or to no class if FOO is NONE,
> or to all classes if FOO is ANY.
That's interesting yet, but I can't find an use case....

For example...

class FOO feature salute do ... end

class HEIR inherit {FRIEND} FOO

class TRAITOR inherit {FOE} FOO

and somewhere else

class PERSON

feature manage(a_foo: FOO) a_foo.salute end

feature handle

    local h: HEIR; t: TRAITOR

    do

        manage(h)

        manage(t)

    end


class FRIEND inherit PERSON

class FOE inherit PERSON

What about calls like a_friend.handle and a_foe.handle? Are those correct?

Doesn't it allow for another form of catcall?