I have used the below construct to generate header files compatible with the C-mode compiler of Visual C++ 6 from Delphi 5 code when Delphi had the -JPH switch (see notes below).
Note that I have not used this since Delphi 5, but the switch has since then been expanded:
Somewhere along the line, the JPHNE switch has been added to the dcc32
command-line compiler:
-JPHNE = Generate C++ .obj file, .hpp file, in namespace, export all
Rudy Velthuis has a nice article using the JPHNE switch.
It certainly does not handle all types, and you will need quite a bit of HPPEMIT and EXTERNALSYM directives.
I uploaded my Delphi 5 to Visual C++ 6 HPP conversion from back then to BitBucket.
It generates the .hpp files to import the DLL that was written in Delphi.
Notes from the Delphi 5 era:
{ Visual C++ 6 does not like nested structs/unions the way that BC++ can handle them.
Visual C++ 6 requires the "typedef" to be present AND the typename AFTER the struct definition.
You will see this when defining TConversationId, TReturnKey and other types that depend on nested structs/unions
The trick is to perform these steps each and every time this unit changes:
- Generate this unit once with all the EXTERNALSYM disabled.
- Then the DCC32 -JPH will generate the basic structs for them.
- Copy all the nested struct and union definitions to this file
- Embed the definitions with (*$HPPEMIT '' *)
- Append the typename at the end of the struct definition
- Enable all the EXTERNALSYM again
- Regenerate the HPP files by using DCC32 -JPH
To make this process easier, we have introduced two new conditional defines:
- BCB - disable EXTERNALSYM, disable HPPEMIT
- VC6 - enable EXTERNALSYM, enable HPPEMIT
A similar thing is with these constructions that VC6 does not like those either:
- short strings (BCB defines them as "SmallString<##>" which VC6 does not like).
- short integers (BCB defines them as "Shortint" so we have included an HPPEMIT for that)
}
{$ifdef win32}
{ important! Makes sure that the all enumerated types fit in exactly one byte each! }
{$Z1}
{ force the C/C++ HPP header files to have the C/C++ compiler pack structure elements on byte boundaries }
{$ifdef BCB}
{$HPPEMIT '#pragma option push -a1' }
{$endif BCB}
{$endif win32}