Given a procedure definition like

procedure checkLibrariesAndConnect(db: TSQLConnection);

is there a more elegant way of performing type-specific actions than

begin
   if db is TPQConnection then begin
   end;
   if db is TIBConnection then begin
   end
end { checkLibrariesAndConnect } ;

i.e. something like case TypeOf(db) ?

No, there is currently no such construct. You could do this though:

=== example begin ===

procedure checkLibrariesAndConnect(db: TSQLConnection);
   procedure SetupPQConnection(db: TSQLConnection);
   // ...
   procedure SetupIBConnection(db: TSQLConnection);
   // ...
type
   TConnectionInitializer = record
     Connection: class of TSQLConnection;
     Setup: procedure(db: TSQLConnection) is nested; // needs
{$modeswitch nestedprocvars}
   end;
const
   ConnectionTypes: array[0..1] of TConnectionInitializer = (
     (Connection: TPQConnection; Setup: @SetupPQConnection),
     (Connection: TIBConnection; Setup: @SetupIBConnection)
   );
var
   conn: TConnectionInitializer;
begin
   for conn in ConnectionTypes do
     if db is conn.Connection then begin
       conn.Setup(db);
       Break;
     end;
end;

=== example end ===

Alternatively if you don't need to check the hierarchy, but can live with an exact match you can do this:

=== example begin ===

procedure checkLibrariesAndConnect(db: TSQLConnection);
begin
   case LowerCase(db.ClassName) of
     // Note: .ClassName won't work here
     'TPQConnection': ...;
     'TIBConnection': ...;
   end;
end;

=== example end ===

Regards,
Sven

Thanks Sven, noted with interest. case LowerCase(...ClassName) looks like "the best of a bad job", provided obviously that it's called infrequently.

In our previous episode, Sven Barth said:

var typ : TCLass;
begin
  typ:=db.classtype;  found:=false;
  while not found and assigned(typ) do
    begin
       case lowercase(typ.classname)
         ..  // must set found=true on match or break.
       end;
      typ:=typ.classparent;
    end;

On 3/1/2013 17:57, Sven Barth wrote:
[...]

is there a bug here? i would expect "LowerCase(anything)" to return all lower case characters... that means that 'TPQConnection' would not match since it contains uppercase characters...

what am i missing?

Thanks, detail noted.