Re: Simple Stream_IO question

["Norman H. Cohen" <ncohen@watson.ibm.com>]

John Raquet wrote:

> If someone could show me what I'm doing wrong in the following code
> sample I'd appreciate it:
> 
> -----------------
> with Ada.Streams.Stream_IO; use Ada.Streams.Stream_IO;
> 
> procedure Foo is
> 
>    F : Float;
>    I : Integer;
> 
>    File : File_Type;
> 
> begin
> 
>    Open(File, In_File, "foo.adb");
> 
>    Float'Read(File, F);
>    Integer'Read(File, I);
> 
>    Close(File);
> 
> end Foo;

The first parameter in a call on a 'Read attribute must be an access
value of a type pointing to Root_Stream'Class.  Package
Ada.Streams.Stream_IO provides such a type, named Stream_Access.  The
package also provides its own type File_Type (the type of File in the
example above) and a function Stream that takes a File_Type parameter
and returns a Stream_Access parameter pointing to a stream that
corresponds to the given file.  Thus you should write:

   Float'Read ( Stream(File), F );
   Integer'Read ( Stream(File), I );

-- 
Norman H. Cohen
mailto:ncohen@watson.ibm.com
http://www.research.ibm.com/people/n/ncohen