🚀 go-pugleaf

Example 1: This is little more than a glorified DLL

Here is what I did:
- Create a new Package, saved as Package1
- Created a new unit, saved as PackageUnit1
- Added function to unit

- Created a new Application, saved as Project1
- Saved the form unit as MainForm
- Added facility to load/unload the package
- Added facility to get and call the procedure

  //-----------------------------------------------------------------------
  // PackageUnit1.h
  #ifndef PackageUnit1H
  #define PackageUnit1H

  extern "C" String PACKAGE __stdcall GetSomeText();

  #endif

  //-----------------------------------------------------------------------
  // PackageUnit1.cpp
  #include <vcl.h>
  #pragma hdrstop

  #include "PackageUnit1.h"
  #pragma package(smart_init)

  extern "C" String __stdcall GetSomeText()
  {
    return "Hola";
  }

  //-----------------------------------------------------------------------
  // MainForm.h
  #ifndef MainFormH
  #define MainFormH

  #include <Classes.hpp>
  #include <Controls.hpp>
  #include <Forms.hpp>
  #include <StdCtrls.hpp>

  class TForm1 : public TForm
  {
    __published:
    TButton *Button1;
    TButton *Button2;
    void __fastcall Button1Click(TObject *Sender);
    void __fastcall Button2Click(TObject *Sender);
    private:
      HMODULE fPackageModule;

    public:
      __fastcall TForm1(TComponent* Owner);
      __fastcall ~TForm1();
  };

  extern PACKAGE TForm1 *Form1;

  #endif

  //-----------------------------------------------------------------------
  // MainForm.cpp
  #include <vcl.h>
  #pragma hdrstop

  #include "MainForm.h"
  #pragma package(smart_init)
  #pragma resource "*.dfm"

  typedef String (__stdcall *TGetSomeText)();

  TForm1 *Form1;

  __fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner)
  {
  }

  __fastcall TForm1::~TForm1()
  {
    if (fPackageModule)
    {
      UnloadPackage(reinterpret_cast <unsigned> (fPackageModule));
      fPackageModule = 0;
    }
  }

  void __fastcall TForm1::Button1Click(TObject *Sender)
  {
    if (!fPackageModule)
    {
      fPackageModule = reinterpret_cast <HMODULE>
        (LoadPackage("Package1.bpl"));
      if (!fPackageModule)
        throw Exception("Could not load package");
    }
  }

  void __fastcall TForm1::Button2Click(TObject *Sender)
  {
    if (!fPackageModule)
      throw Exception("Module hasn't been loaded yet");

    TGetSomeText  fptr = reinterpret_cast <TGetSomeText>
      (::GetProcAddress(fPackageModule, "GetSomeText"));
    if (!fptr)
      throw Exception("Could not find procedure");

    ShowMessage(fptr());
  }

Note the use of extern "C" and __stdcall in the exported function.  extern
"C" removes name mangling and __stdcall removes the preceeding underscore.