External ACCESS VIOLATION error accessing a Class declared in another unit

[AgriMensor]

Laz IDE (2.2.6) under Windows 10 repeatedly gives this runtime error, even though it has successfully compiled before, so something must have happened! The Class in question is declared in Unit sbClrMsg:

Code: Pascal  [Select][+][-]

1. uses
2.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, ExtCtrls,
3.   Buttons, Switches, ComCtrls, ECProgressBar, ECSwitch, InterfaceBase, Interfaces,
4.  
5.   {WordPlay Additionals}
6.   BlowFish, ComObj, DOS, ExtDlgs, LCLIntf, LCLType, Math,
7.   //* OSVerInfo,
8.   VersionTypes, Variants, Win32Proc;
9.  
10. type
11.  
12.   { TfrmsbClrDlg }
13.  
14.   TfrmsbClrDlg = class(TForm)
15.     bbtLeft1: TBitBtn;
16.     bbtMiddle1: TBitBtn;
17.     bbtRight1: TBitBtn;
18.     imgMB_ICON: TImage;
19.     lblText: TLabel;
20.     lblHdr: TLabel;
21.     pnlBkgClr: TPanel;
22.     procedure bbtLeft1Click(Sender: TObject);
23.     procedure bbtMiddle1Click(Sender: TObject);
24.     procedure bbtRight1Click(Sender: TObject);
25.  
26.   private
27.  
28.   public
29.  
30.   end;
31.  
32. var
33.   frmsbClrDlg: TfrmsbClrDlg;
34.  
35. implementation
36.  
37. {$R *.lfm}
38.  
39. { TfrmsbClrDlg }
40.  
41. uses
42.  {Placed here rather than in Interface section to avoid circular references}
43.   WordPlaySuperMsgVersion2;
44.  
45. procedure TfrmsbClrDlg.bbtLeft1Click(Sender: TObject);
46. begin
47.   sbClrDlgResult := mrYes;
48. end;
49.  
50. procedure TfrmsbClrDlg.bbtMiddle1Click(Sender: TObject);
51. begin
52.   sbClrDlgResult := mrNo;
53. end;
54.  
55. procedure TfrmsbClrDlg.bbtRight1Click(Sender: TObject);
56. begin
57.   sbClrDlgResult := mrCancel;
58. end;
59.  
60. end.
61.  

The offending Method in the calling Unit WordPlaySuperMsgVersion2 is this and the offending statement is frmsbClrDlg.lblHdr.Caption := 'Confirm program exit . . .';

Code: Pascal  [Select][+][-]

1. Procedure TForm1.btnQuitClick(Sender: TObject);
2. Begin
3.         Form1.Height := MainFormExtendedHeight; // Retrieve correct height for Main form
4.         Begin //* Setup the message form, display it and interrogate Modal Result
5.         frmsbClrDlg.lblHdr.Caption := 'Confirm program exit . . .';
6.         frmsbClrDlg.lblText.Caption := 'Are you sure you want to'
7.                            +sLineBreak + 'end the program?';
8.         frmsbClrDlg.lblText.Font.Height := 20; //* Size the Text
9.         frmsbClrDlg.imgMB_ICON.Picture.graphic.LoadFromFile(ExtractFilePath(ParamStr(0)) + 'Warning@3x.ico');
10.         frmsbClrDlg.bbtLeft1.Caption := '&Yes';
11.         frmsbClrDlg.bbtLeft1.Kind := bkYes;
12.         frmsbClrDlg.bbtRight1.Caption := '&No';
13.         frmsbClrDlg.bbtRight1.Kind := bkNo;
14.         frmsbClrDlg.bbtLeft1.Visible := True;
15.         frmsbClrDlg.bbtMiddle1.Visible := False;
16.         frmsbClrDlg.bbtRight1.Visible := True;
17.         Form1.Hide; //* until next form is dismissed
18.         frmsbClrDlg.ShowModal; //* Display the next form
19.         If sbClrDlgResult = mrYes Then Form1.Close Else Form1.Show;
20.     End;
21. End;

Can anyone please help identify what I (or the IDE) are doing wrong? Thx!

[alpine]

Is the frmsbClrDlg auto-created in Project Options\Forms?

[AgriMensor]

Thanks, alpine!.
The answer to your question is "No". I have, however, tried it and I get the following error messages in the .lpr file (WPSMV2.lpr).

[AgriMensor]

Compile Project, Target: WPSMV2.exe: Exit code 1, Errors: 2
WPSMV2.lpr(24,26) Error: Identifier not found "TfrmsbClrDlg"
WPSMV2.lpr(24,40) Error: Identifier not found "frmsbClrDlg"

[cdbc]

Hi
USES is missing a unit.
Regards Benny

[AgriMensor]

Thanks, cdbc!

I can't see that a Unit is missing in the calling routine:

Code: Pascal  [Select][+][-]

1. unit WordPlaySuperMsgVersion2;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6. {Items declared in the INTERFACE section are Global}
7.  
8. uses
9.   {LCL and 3rd-party Components}
10.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, ExtCtrls,
11.   ComCtrls, Buttons, ECProgressBar, ECSwitch, InterfaceBase, Interfaces,
12.   Switches, Types,
13.   {WordPlay Additionals}
14.   BlowFish, ComObj, DOS, ExtDlgs, LCLIntf, LCLType, Math, sbClrMsg,
15.   sbSuperMsg2Unit, Settings,
16.   //* OSVerInfo,
17.   VersionTypes, Variants, Win32Proc;

and in the called method (sbClrMsg), the caller appears in a Uses statement in the Implementation section:

Code: Pascal  [Select][+][-]

1. implementation
2.  
3. {$R *.lfm}
4.  
5. { TfrmsbClrDlg }
6.  
7. uses
8.  {Place here rather than in Interface section to avoid circular references:}
9.   WordPlaySuperMsgVersion2;

[cdbc]

Hi
Look in "WPSMV2.lpr"...
:: In lazarus:
- 'Project' -> 'View Source'...
Regards Benny

[AgriMensor]

Hi Benny!

I have tried shoving units from Available forms to Auto-create forms in Project Options --> Forms and in the .lpr file (see my previous response to alpine). Here is the .lpr:

Code: Pascal  [Select][+][-]

1. program WPSMV2;
2.  
3. {$mode objfpc}{$H+}
4.  
5. uses
6.   {$IFDEF UNIX}
7.   cthreads,
8.   {$ENDIF}
9.   {$IFDEF HASAMIGA}
10.   athreads,
11.   {$ENDIF}
12.   Interfaces, // this includes the LCL widgetset
13.   Forms,
14.   { you can add units after this }
15.   WordPlaySuperMsgVersion2;
16.  
17. {$R *.res}
18.  
19. begin
20.   RequireDerivedFormResource:=True;
21.   Application.Scaled:=True;
22.   Application.Initialize;
23.   Application.CreateForm(TForm1, Form1);
24.   Application.Run;
25. end.

That didn't work (again, see my reply to alpine), so what exactly are you suggesting?

Thanks!

[cdbc]

Hi
Well, by the looks of it, you're treating the 'dialogform' as if it was auto-created... It's NOT!
so try this:

Code: Pascal  [Select][+][-]

1. program WPSMV2;
2.  
3. {$mode objfpc}{$H+}
4.  
5. uses
6.   {$IFDEF UNIX}
7.   cthreads,
8.   {$ENDIF}
9.   {$IFDEF HASAMIGA}
10.   athreads,
11.   {$ENDIF}
12.   Interfaces, // this includes the LCL widgetset
13.   Forms,
14.   { you can add units after this }
15.   WordPlaySuperMsgVersion2; // this provides the dlgform
16.  
17. {$R *.res}
18.  
19. begin
20.   RequireDerivedFormResource:=True;
21.   Application.Scaled:=True;
22.   Application.Initialize;
23.   Application.CreateForm(TForm1, Form1);
24.   Application.CreateForm(TfrmsbClrDlg, frmsbClrDlg); // HERE
25.   Application.Run;
26. end.

If I've got the names right, this should get you out of trouble... 
Regards Benny

[AgriMensor]

Thanks for your persistence in trying to help, Benny!  :-)
Unfortunately, although I have tried your suggestion again, this didn't get me out of trouble as it duplicates exactly what I tried before in my response to the post from alpine, i.e. it gives the following error messages:

Compile Project, Target: WPSMV2.exe: Exit code 1, Errors: 2
WPSMV2.lpr(24,26) Error: Identifier not found "TfrmsbClrDlg"
WPSMV2.lpr(24,40) Error: Identifier not found "frmsbClrDlg"

I think I'll try to  manually create the form and see how that goes, but if you (or other forum members) can suggest something else, I'd be grateful!
The code has worked OK before, so I've probably lost something important along the way when I started a new project in a clean directory. But, I've no ide what! :-(

Steve

[cdbc]

Hi Steve
Did you by any chance move those type & variable to 'implementation', i.e.: 'out of sight'?!?
...Otherwise, you'll have to upload a zip with the offending parts, preferably compilable, so we can see / touch for ourselves... Most of the times it's just a small move of code or an oversight...
Regards Benny

[alpine]

Compile Project, Target: WPSMV2.exe: Exit code 1, Errors: 2
WPSMV2.lpr(24,26) Error: Identifier not found "TfrmsbClrDlg"
WPSMV2.lpr(24,40) Error: Identifier not found "frmsbClrDlg"

You don't have sbClrMsg
included in the uses section of WPSMV2.lpr. (Which is parsed as represents the project).

Benny pointed it out in reply #4.

How did this source file sbClrMsg.pas even get into your project? Copied from another folder? If so - make sure that every time you do this you add the file into the Project Inspector.
And then, if you're not certain how exactly to create/use/free the form, just list it into 'Auto-create forms:'.

[AgriMensor]

Hi Benny!

Thx for the new post and  helpful comments!
As I have previously posted, the only reference appearing in an Implementation section is this, which is in the sbClrMsg unit:

Code: Pascal  [Select][+][-]

1. var
2.   frmsbClrDlg: TfrmsbClrDlg;
3.  
4. implementation
5.  
6. {$R *.lfm}
7.  
8. { TfrmsbClrDlg }
9.  
10. uses
11.  {Placed here rather than in Interface section to avoid circular references:}
12.   WordPlaySuperMsgVersion2;

Thx!

[cdbc]

Hi
Na! Then try this:

Code: Pascal  [Select][+][-]

1. program WPSMV2;
2.  
3. {$mode objfpc}{$H+}
4.  
5. uses
6.   {$IFDEF UNIX}
7.   cthreads,
8.   {$ENDIF}
9.   {$IFDEF HASAMIGA}
10.   athreads,
11.   {$ENDIF}
12.   Interfaces, // this includes the LCL widgetset
13.   Forms,
14.   sbClrMsg,  // <-- HERE
15.   WordPlaySuperMsgVersion2;
16.  
17. {$R *.res}
18.  
19. begin
20.   RequireDerivedFormResource:=True;
21.   Application.Scaled:=True;
22.   Application.Initialize;
23.   Application.CreateForm(TForm1, Form1);
24.   Application.CreateForm(TfrmsbClrDlg, frmsbClrDlg); // HERE
25.   Application.Run;
26. end.

Regards Benny

[AgriMensor]

Hi alpine, Hi Benny!

Thank you both very much for your perseverance and help with this issue :-)

Of course, you've both come up with the same solution - my incompetence in missing that I'd left out sbClrMsg in the .lpr Uses statement. How many times have I stared at it and not noticed??? Urgh - a schoolboy error on my part from someone who started using Pascal when Delphi 2 was a boy!!!

Code: Text  [Select][+][-]

1. "How did this source file sbClrMsg.pas even get into your project? Copied from another folder? If so - make sure that every time you do this you add the file into the Project Inspector.
2. And then, if you're not certain how exactly to create/use/free the form, just list it into 'Auto-create forms:'.

It got into the project because I save most of my code in a backup repository of .txt files. I copied and pasted several of these Units into the new project Units and removed those Units names in the Uses statements when they were no longer necessary. I must have accidently deleted "sbClrMsg," when I was doing this - that's the only thing I can think of. That's no excuse for not having spotted such a simple error though :-(

It's now working fine. Once again, many thanks to you both :-)

Steve