Jean Vezina said:
> I am wondering if the following example is valid:

No, it is not.

> CLASS(*),POINTER::X
> INTEGER,TARGET::I=3
> REAL,TARGET::A=12.4
> CHARACTER(3),TARGET::C='ABC'
> X=>I
> PRINT *,X
> X=>A
> PRINT *,X/4.

There is no user-defined OPERATOR(/) in sight,
and intrinsic division is only defined for numeric types.
CLASS(*) has no type.

> X=>C
> PRINT *,'Length=',LEN(X),' Value=',X

The intrinsic function LEN requires a CHARACTER argument.
CLASS(*) has no type.

> END
> 
> Is a  SELECT TYPE  construct necessary here to give to the compiler a 
> hint of the type of  X at compile time ?

It's not a "hint" of the type of X; CLASS(*) doesn't have any intrinsic
operations, you have to define them yourself if you want them.

Which will indeed eventually boil down to doing a SELECT TYPE somewhere to
detect the type and act appropriately.

There are (at least) two ways of thinking about this:
(1) There is a root type "*", which has no intrinsic operations defined on
    it, and from which all other types are extended.  Furthermore, it has
    no deferred operations, so in order to do any operation on something
    declared to be type "*" you cannot override the operations in the root
    type (since there are not any), but must use SELECT TYPE (or, in the
    case of SEQUENCE/BIND(C) types, unsafe pointer assignment) to get to
    a type which does have the required operations.

(2) There is no root type, and an entity of CLASS(*) has no type.  Having
    no type, it has no operations - not even including assignment.  Thus to
    perform any operation on a CLASS(*) entity you must use SELECT TYPE et
    cetera.

The description in the standard follows model (2).

The only sort-of exceptions are that
  - an ALLOCATABLE or POINTER entity of CLASS(*) has the ALLOCATABLE or
    POINTER operations of cloning (viz ALLOCATE(...,SOURCE=...)) and
    deallocation;
  - the various intrinsic functions which work on "any type" also work on
    CLASS(*).  That does not include things like LEN, but does include
    things like SIZE, LBOUND, RESHAPE, ...

> AVERTISSEMENT DE CONFIDENTIALITE                   

Hmm, I'm not sure how to interpret that on a public email list.

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