[Oberon] Case statements containing base type labels

Diego Sardina dsar at eml.cc
Mon Aug 28 13:21:52 CEST 2023

On Mon, Aug 28, 2023, at 13:15, joerg.straube at iaeth.ch wrote:
> August
> In Oberon-07 it is defined as follows:
> The type T of the case expression (case variable) may also be a record or pointer type. Then the
> case labels *must be extensions of T*, and in the statements Si labelled by Ti, the case variable is
> considered as of type Ti.
> PROCEDURE Draw (s: Shape)
>   CASE s OF
>        Rectangle: ... |
>        Circle: ... |
>        Shape: ...  this is not allowed as “Shape” is not an extension of “Shape”
>    END
> END Draw;
> Jörg

A record type is also an extension of itself. So that is valid.

Diego Sardina
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