Newbie Var assignment

[weitsprung]

How can I make it so that the passed in variable actually gets set in SetVar procedure?

Code: [Select]

unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    procedure SetVar(avariable: Variant; const avalue: Variant)  ;
  end;

var
  Form1: TForm1;

  b: Boolean;
  s: String;
  i: Integer;


implementation

{$R *.lfm}

procedure TForm1.SetVar(avariable: Variant; const avalue: Variant) ;
begin
  if (avariable <> avalue) then
  begin
    avariable := avalue;
    showmessage('inside: ' + string(avariable));
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  s := 'boat';
  ShowMessage('before: ' + s);
  SetVar(s, 'car');
  ShowMessage('after: ' + s);
end; 

[taazz]

Code: [Select]

  //.....
  private
    procedure SetVar(avariable: Variant; const avalue: Variant)  ;
//...
implementation

{$R *.lfm}

procedure TForm1.SetVar(var avariable: Variant; const avalue: Variant) ;
begin //......
 

[weitsprung]

that results in

Error: Call by var for arg no. 1 has to match exactly: Got "AnsiString" expected "Variant"

[taazz]

that results in

Error: Call by var for arg no. 1 has to match exactly: Got "AnsiString" expected "Variant"

so do what the message says change the "S" declaration to variant.

[cdbc]

Hi
quote from taazz:
  //.....
  private
    procedure SetVar(var avariable: Variant; const avalue: Variant)  ;
//...
implementation

{$R *.lfm}

procedure TForm1.SetVar(var avariable: Variant; const avalue: Variant) ;
begin //......

Regards Benny

[munair]

Code: [Select]

  //.....
  private
    procedure SetVar(avariable: Variant; const avalue: Variant)  ;
//...
implementation

{$R *.lfm}

procedure TForm1.SetVar(var avariable: Variant; const avalue: Variant) ;
begin //......
 

Taaz means he forgot to adjust the declaration in his example.

Code: [Select]

  //.....
  private
    procedure SetVar(var avariable: Variant; const avalue: Variant)  ;
//...
implementation

{$R *.lfm}

procedure TForm1.SetVar(var avariable: Variant; const avalue: Variant) ;
begin //......
  

[taazz]

yeah i copy pasted a couple of times between various things I did at the moment and ended up missing a var declaration sorry about that, but my second post was about changing global variable declaration from

Code: [Select]

S:string; to

Code: [Select]

S:Variant;; here is the complete unit with all the changes required to make work.

Code: [Select]


unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    procedure SetVar(var aVariable: Variant; const avalue: Variant)  ;
  end;

var
  Form1: TForm1;

  b: Boolean;
  s: Variant;
  i: Integer;


implementation

{$R *.lfm}

procedure TForm1.SetVar(var aVariable: Variant; const avalue: Variant) ;
begin
  if (avariable <> avalue) then
  begin
    avariable := avalue;
    showmessage('inside: ' + string(avariable));
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  s := 'boat';
  ShowMessage('before: ' + s);
  SetVar(s, 'car');
  ShowMessage('after: ' + s);
end;