CODEWITHSUNDEEP
delphi
Glen Morse
Glen Morse

Reputation: 2593

Check if component is either type

I am trying to check if a component is type TMachine or TLabel if so i want it to free it as long as its NOT Label1 or label2

but it will not let me do an OR on if Components[I] is (TMachine) or (TLabel) then Any way to fix this?

    procedure TfDeptLayout.FormClose(Sender: TObject; var Action: TCloseAction);
var
  I: Integer;
begin
     for I := ComponentCount -1 downto 0 do
      begin
          if Components[I] is (TMachine) or (TLabel) then
              if Components[I].Name <> Label2.Name then
                if Components[I].Name <> label3.Name then
                  components[I].Free;
      end;
end;

Upvotes: 0

Views: 1692

Answers (1)

Gerry Coll
Gerry Coll

Reputation: 5975

You cannot use or in that way, you need to "repeat" the is as well.

You also don't need to use Components[I].Name, it suffices to simpy compare the Components[I] reference with the Label1 and Label2 references:

procedure TfDeptLayout.FormClose(Sender: TObject; var Action: TCloseAction);
var
  I: Integer;
begin
     for I := ComponentCount -1 downto 0 do
     begin
       if (Components[I] is TMachine) or (Components[I] is TLabel) then
         if Components[I] <> Label2 then
           if Components[I] <> label3 then
             components[I].Free;
      end;
end;

it would also be possible (but maybe less readable) to combine all of the conditionals:

procedure TfDeptLayout.FormClose(Sender: TObject; var Action: TCloseAction);
var
  I: Integer;
  comp: TComponent;
begin
     for I := ComponentCount -1 downto 0 do
     begin
       Comp := Components[I];
       if (Comp is TMachine) then
         Comp.Free
       else if (Comp is TLabel) and (Comp <> Label2) and (Comp <> Label3) then
         Comp.Free;
     end;
end;

As an aside, it is best to give components that are referred to in code a meaningful name, rather than using the default Label1, Label2... names

Upvotes: 3

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