[IronPython] Using a c library as a dll or assembly

[Anders Elfgren]

Hi, thanks for the comments!
In this case, I'm not trying to access a class, just a simple function
that takes a string (char* ) and returns an int. I was hoping that would
make it easier. 
 
I've compiled the dll with /CLR and I can load it like this:
 
import clr
clr.AddReference("System.Windows.Forms")
clr.LoadAssemblyByName("AdfDll_R.dll")
 
However, I still can't access anything inside it. Do I need to do
something more? (if I try to load a dll that doesn't exist I get an
error, so I'm assuming that there's not a problem with my dll). I've
tried adding an import but I just get No module named AdfDll_R.
 
 
The function is declared as:
 
#ifdef __cplusplus
extern "C" {
#endif
 
uint32   AdfHash(const char *str);

}
 
But when I try to call it, it doesn't work:
NameError: name 'AdfHash' not defined
 
 
 
I'm exporting the functions using a def file that looks (pretty much)
like this:
LIBRARY   AdfDll_R
EXPORTS
 
; from Adf.h
   AdfHash
 
I'm using IronPython 1.1.1, but if it helps I'll be glad to change to
another version. 
 
/Anders

________________________________

From: users-bounces at lists.ironpython.com
[mailto:users-bounces at lists.ironpython.com] On Behalf Of Curt
Hagenlocher
Sent: den 31 juli 2008 20:21
To: Discussion of IronPython
Subject: Re: [IronPython] Using a c library as a dll or assembly


It wouldn't be sufficient to recompile with /clr.  When you do that,
your classes don't automatically become managed classes.  You would
still need to either modify your classes or to create wrappers using
C++/CLI (http://en.wikipedia.org/wiki/C%2B%2B/CLI).  In order for a C++
class to be visible to IronPython, it would need to be declared as a
"ref class" -- you can see more about that at the referenced Wikipedia
article.

 
On Thu, Jul 31, 2008 at 9:22 AM, Anders Elfgren
<anders.elfgren at avalanchestudios.se> wrote:


	Hi, 
	 
	First let me say that I'm new to Iron Python, but at least I've
read this in the FAQ.. :)
	 
	Q: How do I build and call into PYD libraries?
	A: IronPython does not support using PYDs built for CPython
since they leverage implementation details of CPython.  You can get a
similar effect for new "PYD"s you would like to implement by writing
them in C# or VB and building a DLL for .NET.
	 
	That said, I've got some questions to see if what I'm doing is
possible anyway.
	 
	We've got a c library of which most of the code has also been
written in Python. We want to create an editor using .net forms which we
can use to edit some files, and to do that we need some data structures
that exist in this library. 
	 
	My current idea is to interface against the python library using
IronPython, and then accessing the datastructures through that in C#
(although if absolutely necessary, we could write the editor in
IronPython too). The thing that is standing against me now is that one
function that exists a small C dll. Since IronPython can't access this
(unless this has changed since the FAQ was written?), I was thinking
that maybe I can compile the dll using the /clr flag and thus get a .net
assembly. Would I then be able to use the function?
	 
	The Python code just tries to import it:
	import AvHash
	 
	And then use it..
	def AdfHash(str):
	    return AvHash.HashString(str)
	 
	 
	At the import statement, this error is raised:
	Traceback (most recent call last):
	  File X:\ctg\libs\ADF\main\common\modeditor.ipy, line 20, in
Initialize
	  File , line 0, in __import__##4
	  File X:\ctg\libs\ADF\main\common\AdfLib.py, line 1, in
Initialize
	  File , line 0, in __import__##4
	ImportError: No module named AvHash
	 
	 
	 
	Or is there some other solution? I've just started researching
how to interface between C/C#/Python/IronPython so there may well be
things I haven't heard of...
	I hope I've made my problem clear, thanks for any responses. :)
	 
	/Anders
	 

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