[fpc-pascal] The 'correct' way to debug applications

[Graeme Geldenhuys]

Hi,

I'm busy implementing and correcting Application.CreateForm() in fpGUI. 
Everything looked and worked fine until I enabled 'heaptrc' to see if I 
have memory leaks.

Normally I just look at the output, randomly picking a method listed by 
heaptrc output and go through the code slowly. 9 out of 10 times I spot 
the problem and fix it.

Today I've been sitting for 4 hours trying to find the problem and I'm 
still not the wiser!  Is there a 'correct' process to follow and debug 
Free Pascal applications. Something like a system or steps to follow, to 
get to the problem area. Is there a website or book that covers 
debugging Object Pascal (or just Pascal) applications?

Any help, references or links would be greatly appreciated at this time. 
BTW: When I run my test application via GDB I get only 3 lines of output 
which simply reference the Destroy() method, nothing more. :-(


-------------------------
Heap dump by heaptrc unit
1190 memory blocks allocated : 116862/118456
1181 memory blocks freed     : 115895/117472
9 unfreed memory blocks : 967
True heap size : 327680
True free heap : 326080
Should be : 326192
Call trace for block $B7BCC678 size 12
   $08056AD2
   $0807FCC0  TFPGAPPLICATION__GETFONT,  line 846 of 
/home/graemeg/programming/fpGUI/src/corelib/fpgfx.pas
   $0807F6BD  FPGGETFONT,  line 754 of 
/home/graemeg/programming/fpGUI/src/corelib/fpgfx.pas
   $080C5477  TFPGBUTTON__SETFONTDESC,  line 201 of gui_button.pas
   $080F1807  TTESTFORM__AFTERCREATE,  line 68 of frm_test.pas
   $080AEDBE  TFPGFORM__CREATE,  line 226 of gui_form.pas
   $080F1654  TTESTFORM__CREATE,  line 50 of frm_test.pas
   $080A2CC0  TFPGAPPLICATIONBASE__CREATEFORM,  line 1899 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
Call trace for block $B7A9A648 size 120
   $08056AD2
   $08082B6B  TFPGWINDOW__CREATE,  line 1370 of 
/home/graemeg/programming/fpGUI/src/corelib/fpgfx.pas
   $080ACF26  TFPGWIDGET__CREATE,  line 261 of 
/home/graemeg/programming/fpGUI/src/corelib/gfx_widget.pas
   $080C54EF  TFPGBUTTON__CREATE,  line 207 of gui_button.pas
   $080F17AB  TTESTFORM__AFTERCREATE,  line 62 of frm_test.pas
   $080AEDBE  TFPGFORM__CREATE,  line 226 of gui_form.pas
   $080F1654  TTESTFORM__CREATE,  line 50 of frm_test.pas
   $080A2CC0  TFPGAPPLICATIONBASE__CREATEFORM,  line 1899 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
Call trace for block $B7BCC628 size 16
   $0805B96B
   $0806A4F7
   $080717A5
   $080A06DA  TFPGWINDOWBASE__CREATE,  line 953 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
   $080A6D3A  TFPGWINDOWIMPL__CREATE,  line 1594 of gfx_x11.pas
   $08082AE1  TFPGWINDOW__CREATE,  line 1353 of 
/home/graemeg/programming/fpGUI/src/corelib/fpgfx.pas
   $080ACF26  TFPGWIDGET__CREATE,  line 261 of 
/home/graemeg/programming/fpGUI/src/corelib/gfx_widget.pas
   $080C54EF  TFPGBUTTON__CREATE,  line 207 of gui_button.pas
Call trace for block $B7BCC5D8 size 16
   $08056AD2
   $0806B477
   $08070FF3
   $080717A5
   $080A06DA  TFPGWINDOWBASE__CREATE,  line 953 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
   $080A6D3A  TFPGWINDOWIMPL__CREATE,  line 1594 of gfx_x11.pas
   $08082AE1  TFPGWINDOW__CREATE,  line 1353 of 
/home/graemeg/programming/fpGUI/src/corelib/fpgfx.pas
   $080ACF26  TFPGWIDGET__CREATE,  line 261 of 
/home/graemeg/programming/fpGUI/src/corelib/gfx_widget.pas
Call trace for block $B7BCC588 size 8
   $08056AD2
   $08070FF3
   $080717A5
   $080A06DA  TFPGWINDOWBASE__CREATE,  line 953 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
   $080A6D3A  TFPGWINDOWIMPL__CREATE,  line 1594 of gfx_x11.pas
   $08082AE1  TFPGWINDOW__CREATE,  line 1353 of 
/home/graemeg/programming/fpGUI/src/corelib/fpgfx.pas
   $080ACF26  TFPGWIDGET__CREATE,  line 261 of 
/home/graemeg/programming/fpGUI/src/corelib/gfx_widget.pas
   $080C54EF  TFPGBUTTON__CREATE,  line 207 of gui_button.pas
Call trace for block $B7A8A348 size 308
   $08056AD2
   $080F17AB  TTESTFORM__AFTERCREATE,  line 62 of frm_test.pas
   $080AEDBE  TFPGFORM__CREATE,  line 226 of gui_form.pas
   $080F1654  TTESTFORM__CREATE,  line 50 of frm_test.pas
   $080A2CC0  TFPGAPPLICATIONBASE__CREATEFORM,  line 1899 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
   $080842D7  TMAINFORM__NEWFORMCLICK,  line 49 of frm_main.pas
   $080C5FEB  TFPGBUTTON__CLICK,  line 466 of gui_button.pas
   $080C5DA0  TFPGBUTTON__DORELEASE,  line 385 of gui_button.pas
Call trace for block $B7F5F308 size 19
   $08051C2F
   $080AEDBE  TFPGFORM__CREATE,  line 226 of gui_form.pas
   $080F1654  TTESTFORM__CREATE,  line 50 of frm_test.pas
   $080A2CC0  TFPGAPPLICATIONBASE__CREATEFORM,  line 1899 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
   $080842D7  TMAINFORM__NEWFORMCLICK,  line 49 of frm_main.pas
   $080C5FEB  TFPGBUTTON__CLICK,  line 466 of gui_button.pas
   $080C5DA0  TFPGBUTTON__DORELEASE,  line 385 of gui_button.pas
   $080C5F07  TFPGBUTTON__HANDLELMOUSEUP,  line 431 of gui_button.pas
Call trace for block $B7A9A588 size 120
   $08056AD2
   $08082B6B  TFPGWINDOW__CREATE,  line 1370 of 
/home/graemeg/programming/fpGUI/src/corelib/fpgfx.pas
   $080ACF26  TFPGWIDGET__CREATE,  line 261 of 
/home/graemeg/programming/fpGUI/src/corelib/gfx_widget.pas
   $080AED2F  TFPGFORM__CREATE,  line 214 of gui_form.pas
   $080F1654  TTESTFORM__CREATE,  line 50 of frm_test.pas
   $080A2CC0  TFPGAPPLICATIONBASE__CREATEFORM,  line 1899 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
   $080842D7  TMAINFORM__NEWFORMCLICK,  line 49 of frm_main.pas
   $080C5FEB  TFPGBUTTON__CLICK,  line 466 of gui_button.pas
Call trace for block $B7A921E8 size 348
   $08056AD2
   $080A2CC0  TFPGAPPLICATIONBASE__CREATEFORM,  line 1899 of 
/home/graemeg/programming/fpGUI/src/corelib/gfxbase.pas
   $080842D7  TMAINFORM__NEWFORMCLICK,  line 49 of frm_main.pas
   $080C5FEB  TFPGBUTTON__CLICK,  line 466 of gui_button.pas
   $080C5DA0  TFPGBUTTON__DORELEASE,  line 385 of gui_button.pas
   $080C5F07  TFPGBUTTON__HANDLELMOUSEUP,  line 431 of gui_button.pas
   $080AD58B  TFPGWIDGET__MSGMOUSEUP,  line 445 of 
/home/graemeg/programming/fpGUI/src/corelib/gfx_widget.pas
   $08056E79
-------------------------


Regards,
   - Graeme -


_______________________________________________________
fpGUI - a cross-platform GUI toolkit using Free Pascal
http://opensoft.homeip.net/fpgui/