Re: schema pointer compatibility

On 13 Aug 2012 at 10:46, Jay Michael wrote:

 Why isn't the address of an object of a schema type an acceptable

value for a pointer to the (undiscriminated) schema type?

type sptr_type = ^ string ; type sptr_array_type( n : integer ) = array [ 1 .. n ] of sptr_type ; type sptr_array_ptr_type = ^ sptr_array_type ;

const s1 = 's1' ; const s2 = 's2' ; const s3 = 's3' ;

const slist : sptr_array_type(3) = ( @s1, @s2, @s3 ) ;

var slist_ptr : sptr_array_ptr_type = @slist ;

t12.pas:23: error: assignment from incompatible pointer type

 I got the same error when I changed "slist" (the object of the

discriminated schema type) from a "const" to a "var". I got the same error when I tried using an assignment statement:

      var slp : sptr_array_ptr_type ;
      ...
      slp := @slist ;

 If a discriminated instance of a schema type isn't quite the

same type as the undiscriminated type, then when would I ever be able to use the address of an object as a value for a pointer to the undiscriminated type? (without coercion, that is)

Because what you are trying to do is rejected by the standards that you are implicitly following. Compile with "--no-typed-address", and it will compile.

Best regards, The Chief -------- Prof. Abimbola A. Olowofoyeku (The African Chief) web: http://www.greatchief.plus.com/