## Get MOC_GridDlg.cpp to compile

[khartmansjsu]

Goal: compile MOC_GridDlg.cpp

Summary

Changelog:

• On line 4 of MOC_GridDlg.cpp, comment out dependency on stdafx.h At first glance, and referring to the last comment on this issue (where CreatMOCGrid is seen to be called from only 'MOC_GridDlg.cpp on line 540), I identify a function method of the class CMOC_GridDlg, CMOC_GridDlg::OnCalcMOCBUTTON(). CreatMOCGrid is called from within this function. Additionally, this appears to be the only block of code thus far which could be run standalone, with the replacement of some lines of code, such as line 517, where AfxMessageBox() is used to print a fatal error message. I think that a main.cpp script which contains a form of lines 503-547 is a good path to take in implementing the above plan of action. Still, I will go through the steps to remove dependencies of MOC_GridDlg.cpp on packages which cannot exist in linux. Attempts 1 - ___ itemize these steps.

Attempt 1:

[khartm12@integrity MOC_Grid_BDE]$ g++ MOC_GridDlg.cpp -o MOC_GridDlgTest
MOC_GridDlg.cpp:4:10: fatal error: stdafx.h: No such file or directory
    4 | #include "stdafx.h"
      |          ^~~~~~~~~~
compilation terminated.
[khartm12@integrity MOC_Grid_BDE]$

• Change: On line 4 of MOC_GridDlg.cpp, comment out dependency on stdafx.h
• Reason: stdafx.h is another Windows MFC library. It doesn't exist, and we don't want it to in order for this code to compile.

Attempt 2:

[khartm12@integrity MOC_Grid_BDE]$ g++ MOC_GridDlg.cpp -o MOC_GridDlgTest
MOC_GridDlg.cpp:4:10: fatal error: stdafx.h: No such file or directory
    4 | #include "stdafx.h"
      |          ^~~~~~~~~~
compilation terminated.
[khartm12@integrity MOC_Grid_BDE]$ g++ MOC_GridDlg.cpp -o MOC_GridDlgTest
In file included from MOC_GridDlg.cpp:5:
MOC_Grid.h:12:3: error: #error include 'stdafx.h' before including this file for PCH
   12 |  #error include 'stdafx.h' before including this file for PCH
      |   ^~~~~
MOC_GridDlg.cpp:14:10: fatal error: direct.h: No such file or directory
   14 | #include "direct.h"
      |          ^~~~~~~~~~
compilation terminated.
[khartm12@integrity MOC_Grid_BDE]$

• Still getting a compile time issue related stdafx.h, but the issue is coming from MOC_Grid.h now instead of MOC_GridDlg.cpp.
• Change: On line 5 of MOC_GridDlg.cpp, comment out the include statement for MOC_Grid.h.
• Reason: MOC_Grid.h is the main header file for the application, but doesn't appear to contain any important code blocks for calculations of MOC contours or streamlines, etc. Rather, it declares a class CMOC_GridApp of type CWinApp. While this is useful for the GUI and application, it is not necessary for the linux version we are developing. Remove it.
• Change: On line 14 of MOC_GridDlg.cpp, comment out the include statement for direct.h.
• Reason: direct.h does not exist in any of this package's three subdirectories. This is why the compiler does not find it. Here, we see some stackoverflow contributors citing wikipeadia that direct.h is a Microsoft Windows specific header file, the utilities of which replaced by including unistd.h in a linux system. I will not do this just yet. I want to first confirm that direct.h is being used in a way that unistd.h can also be used.
• Note: I further corroborated the stackoverflow contributors' citation by finding the official Digital Mars documentation for direct.h. Its compatibility is listed, and does not include Linux systems.

Attempt 3:

see compile_errors2.txt tons of compile time error, unrelated to missing header files or undeclared header files.

• Below, we see the compiler complaining about DECLARE_DYNAMIC, an MFC object which is of course not available in linux.

  MOC_GridDlg.h:18:2: error: ISO C++ forbids declaration of ‘DECLARE_DYNAMIC’ with no type [-fpermissive]
  18 |  DECLARE_DYNAMIC(CMOC_GridDlg);
    |  ^~~~~~~~~~~~~~~

  The plethora of compile-time errors further supports the idea that I should try to extract lines 503-547 from MOC_GridDlg.cpp and make a script which can run in linux, not requiring all the windows dependencies that pop up in the header files' function declarations. There will undoubtedly be more windows dependencies buried in the aforementioned lines of code, but it will at least be a smaller code base to start, and will still ultimately generate output files as the original code does.

Originally posted by @khartmansjsu in https://github.com/khartmansjsu/MOC-Linux/issues/1#issuecomment-1106734644

[khartmansjsu]

Action plan

1. Use lines 503-547 of MOC_GridDlg.cpp as a template for a main.cpp file which will launch this whole MOC code on a linux system. It will make the call to the CreatMOCGrid function which sets into motion the calculation of the method of characteristics grid.
2. Further debug this file, as it will likely not compile the first time because there are still many dependencies which need to be removed from the MOC_GridCalc_BDE.cpp script.