[Tutor] Python C extension - which method?

[Michael C]

Sorry I don't understand your suggestion.

Use "ctypes.CDLL" and "ctypes.WinDLL"

this works,
mydll = cdll.LoadLibrary('test.dll')
print(mydll.sum(3,2))

and this doens't
mydll = cdll('test.dll')
print(mydll.sum(3,2))

What's the syntax of what you suggested?

Thanks

On Mon, May 7, 2018 at 3:15 AM, eryk sun <eryksun at gmail.com> wrote:

> On Sun, May 6, 2018 at 12:49 AM, Brad M <thebigwurst at gmail.com> wrote:
> > If I may ask, what's the difference between these two?
> >
> > 1)
> > import ctypes
> > hello = ctypes.WinDLL('hello', use_last_error=True)
> >
> > 2)
> > from ctypes import cdll
> > hello = cdll.LoadLibrary('hello.dll')
>
> Use ctypes.CDLL and ctypes.WinDLL instead of cdll.LoadLibrary and
> windll.LoadLibrary. The latter is more typing for no benefit and
> prevents using the constructor arguments: handle, mode (POSIX),
> use_errno, and use_last_error (Windows). You need the latter two
> options if the library requires C errno or Windows GetLastError(), in
> which case you should use ctypes.get_errno() or
> ctypes.get_last_error() to get the error values after a C function
> call.
>
> > Both of them can return "1980" from  this:
> >
> > hello.c
> >
> > #include <stdio.h>
> >
> > __declspec(dllexport) int say_something()
> > {
> >     return 1980;
> > }
>
> CDLL is the cdecl calling convention, and WinDLL is stdcall. There is
> no difference in 64-bit Windows (x64 ABI). In 32-bit Windows (x86
> ABI), cdecl has the caller clean the stack (i.e. pop arguments), and
> stdcall has the callee (the called function) clean the stack. cdecl
> allows functions with a variable number of arguments, such as the CRT
> printf function. In MSVC, cdecl is the default convention if you don't
> declare a function as __stdcall. A library can export functions with
> varying calling conventions, so in general you may need to mix CDLL
> and WinDLL.
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