Delphi extension

[Donald L. Dietmeyer]

I was given a libxx.so that was probably written in Delphi.
I need to wrap it so that I can call the functions/procedures
of the library from Python. I tried the usual extension
technique compiling a C file. I don't get anything meaningful
back when I call, so it doesn't work, or I am missing some
critical point. I have spent a good deal of time searching
the net, and found one or two comments about doing the job,
but no evidence that anyone has done it.

I would appreciate any suggestions or advice.
Don

 

[Christopher T King]

I was given a libxx.so that was probably written in Delphi.

I need to wrap it so that I can call the functions/procedures
of the library from Python. I tried the usual extension
technique compiling a C file. I don't get anything meaningful
back when I call, so it doesn't work, or I am missing some
critical point. I have spent a good deal of time searching

I don't know anything about Delphi; it may use a different calling
convention than C (unlikely). If that's the case, however, you're out of
luck unless you can find a Delphi-C or Delphi-Python interface module.

Assuming it uses the C calling convention, you can possibly use the dl
module:

import dl
c=dl.open('/path/to/my/lib.so')
c.call('myfunc',arg1,arg2)

dl is unfortunately limited to passing integers, strings, and NULL, and to
returning integers, so it's likely not to be useful for complex data
structures.

 

[Peter Hansen]

I was given a libxx.so that was probably written in Delphi.
I need to wrap it so that I can call the functions/procedures
of the library from Python. I tried the usual extension
technique compiling a C file. I don't get anything meaningful
back when I call, so it doesn't work, or I am missing some
critical point. I have spent a good deal of time searching
the net, and found one or two comments about doing the job,
but no evidence that anyone has done it.

I would appreciate any suggestions or advice.

Would ctypes work for you? http://starship.python.net/crew/theller/ctypes/

 

[Jarek Zgoda]

I don't know anything about Delphi; it may use a different calling
convention than C (unlikely). If that's the case, however, you're out of
luck unless you can find a Delphi-C or Delphi-Python interface module.

Register is default call convention for libraries written in Delphi, but
one may use any other at will.

 

[John J. Lee]

Register is default call convention for libraries written in Delphi, but
one may use any other at will.

A bit of a Delphic utterance...

Googling, it seems 'Register' is what MSVC calls __fastcall.

Not sure how you tell which Delphi functions obey which calling
convention, but (in the absence of a more polished method) I think I'd
attempt to find that out, then write a thin wrapper of the Delphi
interface in C, with explicit calling convention declarations
(eg. __fastcall), then wrap *that* with SWIG.


John

 

[Christophe Cavalaria]

A bit of a Delphic utterance...

Googling, it seems 'Register' is what MSVC calls __fastcall.

Not sure how you tell which Delphi functions obey which calling
convention, but (in the absence of a more polished method) I think I'd
attempt to find that out, then write a thin wrapper of the Delphi
interface in C, with explicit calling convention declarations
(eg. __fastcall), then wrap *that* with SWIG.


John

Use cdecl in Delphi so declare a function with C calling convention. No need
to create a wraper in C to do that.

procedure DoSomething; cdecl;

 

[John J. Lee]

Use cdecl in Delphi so declare a function with C calling convention. No need
to create a wraper in C to do that.

procedure DoSomething; cdecl;

He probably doesn't even have a Delphi compiler. He just has this
Delphi DLL somebody's given him to wrap.


John