How to refer to a single value from an enumerated type declared in a set type?

[PiedSoftware 3]

In Delphi in System.Class we have this declaration:

TShiftState = set of (ssShift, ssAlt, ssCtrl, ssLeft, ssRight, ssMiddle, ssDouble, ssTouch, ssPen, ssCommand, ssHorizontal);

Given that declaration, how can I declare a variable that will be just one of those values?

[Dmitry Arefiev 103]

var
  s: ssShift .. ssHorizontal;

or upgrade to Delphi 12 and use TShiftStateItem.

[havrlisan 25]

If you're using a Delphi version 10.3 or newer, you can also achieve this by declaring an inline variable:

var
LEnum := ssShift;

 

[Remy Lebeau 1413]

1 hour ago, PiedSoftware said:

Given that declaration, how can I declare a variable that will be just one of those values?

Prior to Delphi 12, the Enum type for TShiftState is anonymous, so you can't declare a variable of that type, at least not directly. With the introduction of Inline Variables and Type Inference in Delphi 10.3, you can do so, but only if you initialize the variable at the same time you declare it, eg:

 var state := ssShift;

This is exactly the kind of situation why several such Sets in the RTL have been re-written in recent versions to separate their Enum types from their Set types. TShiftState was re-written in Delphi 12, it now looks like this:

TShiftStateItem = (ssShift, ssAlt, ssCtrl, ssLeft, ssRight, ssMiddle, ssDouble, ssTouch, ssPen, ssCommand, ssHorizontal);

TShiftState = set of TShiftStateItem;

So, you can now declare a variable of type TShiftStateItem.

Edited 18 hours ago by Remy Lebeau

[Rollo62 538]

Edit:

 

Ok, ok:

procedure HappyAssignmentsFromHappyDeclarations;
var 
   stateOneItem     : TShiftStateItem;
   statesetOneItem  : TShiftState;   
begin
    
    // A single item
    stateOneItem    :=   ssShift;   
    // A set with a single item only
    statesetOneItem := [ ssShift ];
    
end;

 

Edited 10 hours ago by Rollo62

[Anders Melander 1795]

6 minutes ago, Rollo62 said:

Sorry, what are you looking for?

// A single item
var state : TShiftStateItem =   ssShift;
// or
// A set with a single item only
var state : TShiftState     = [ ssShift ];

 

That's assignments. OP is asking for a type declaration.

[Rollo62 538]

Yes, I wanted to clarify WHAT exactly he wants to assign ...

[Lajos Juhász 293]

29 minutes ago, Rollo62 said:

Sorry, what are you looking for?

OP is on older version of Delphi 10.4 your example is Delphi 12.