[Caml-list] match on dynamic type

[Caml-list] match on dynamic type

[Olivier Ricordeau]

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Hi!

I'd like to know how I can make a match on an object's dynamic type. Let
a be an abstract class. Let b and c be two class which inherit from a.
I'd like to write a method which looks like this:

method foo (bar : a) =
    match "a's dynamic type" with
       b -> do_something()
     | c -> do_something_else()

If anyone of you could explain me how to do this... Google didn't really
help me about this, and I didn't find the answer (which is quite rare :)
) in the O'Reilly book.

Cheers

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Re: [Caml-list] match on dynamic type

[Olivier Ricordeau]

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Olivier Ricordeau wrote:
> Hi!
>
> I'd like to know how I can make a match on an object's dynamic type. Let
> a be an abstract class. Let b and c be two class which inherit from a.
> I'd like to write a method which looks like this:
>
> method foo (bar : a) =
>     match "a's dynamic type" with

I meant:
      match "bar's dynamic type" with

>        b -> do_something()
>      | c -> do_something_else()

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Re: [Caml-list] match on dynamic type

[Olivier Ricordeau]

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Olivier Ricordeau wrote:
>>Hi!
>>I'd like to know how I can make a match on an object's dynamic type. Let
>>a be an abstract class. Let b and c be two class which inherit from a.
>>I'd like to write a method which looks like this:
>>
>>method foo (bar : a) =
>>    match "a's dynamic type" with
>
> I meant:
>       match "bar's dynamic type" with
>
>
>>       b -> do_something()
>>     | c -> do_something_else()

According to two mails I've just received from members of this list:
- -> This cannot be done with OCaml
- -> The trick is to add an string attribute (non-mutable) which contains
the dynamic type to the mother class.

Thanks to Basile Starynkevitch and Richard Jones for their help.

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