Calling YAP from C# code

[Daniel Brandur Sigurgeirsson]

Hi all,

I'm one of those very few weird folks that would like to use YAP in a C# program, but I'm having some problems with that.

First, if I call YAP from C# using P/Invoke, I can call YAP_FastInit - it does not seem to give me any errors. However, when I want to call "consult" using the following code:

public void Consult( String strFileName )

{

String strCommand = String.Format( "consult('{0}')", strFileName );

int term = 0;

int goal = YAPWrapper.YAP_ReadBuffer( strCommand, ref term );

int result = YAPWrapper.YAP_RunGoal( goal );

if ( result == 0 )

{

throw new ArgumentException( "Error while trying to consult file " + strFileName );

}

I always get a 0 result from calling YAP_RunGoal. Any ideas why? Is there any way to figure out why running a goal doesn't work? (Any GetLastError function?) Note that I've tried various possibilities with the file name: full path with or without the extension, just the filename again with or without the extension etc.

I suspected that this could be because I'm using P/Invoke to call YAP functions, so I tried linking directly to YAP, but in order to do that I need a .lib file to link against. I could not find it in the download, so I tried building YAP from the instructions given, only using VS2008 instead of VS 6.0. But every time I run that version, I get an error saying that I'm trying to access protected memory, and this happens with the first function I'm calling (YAP_FastInit).

Finally, I tried calling the YAP function directly using ::LoadLibrary( "yap.dll" ) and ::GetProcAddress( hLib, "YAP_FastInit"), but the program I wrote that does that (a simple console program in C++), simply crashes without any warning whatsoever when I try this.

So, are there any ideas on how I can call YAP from a C# program?

Daníel

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[Vitor Santos Costa-2]

Hi Daniel

Sorry again for the long delay.  I sincerely hope this may still be useful :(

On Fri, Apr 3, 2009 at 6:03 AM, Daniel Brandur Sigurgeirsson
<danielbsig@...> wrote:

> Hi all,
> I'm one of those very few weird folks that would like to use YAP in a C#
> program, but I'm having some problems with that.
> First, if I call YAP from C# using P/Invoke, I can call YAP_FastInit - it
> does not seem to give me any errors. However, when I want to call "consult"
> using the following code:
> public void Consult( String strFileName )
> {
> String strCommand = String.Format( "consult('{0}')", strFileName );
> int term = 0;
> int goal = YAPWrapper.YAP_ReadBuffer( strCommand, ref term );
> int result = YAPWrapper.YAP_RunGoal( goal );
> if ( result == 0 )
> {
> throw new ArgumentException( "Error while trying to consult file " +
> strFileName );
> }
> I always get a 0 result from calling YAP_RunGoal. Any ideas why? Is there
> any way to figure out why running a goal doesn't work? (Any GetLastError

I would suggest using printf in the YAP code. It is very primitive, I know.

> function?) Note that I've tried various possibilities with the file name:
> full path with or without the extension, just the filename again with or
> without the extension etc.

It should load from the current directory.

What happens if you try running a goal like "nl". Does it succeed and
generate output?

> I suspected that this could be because I'm using P/Invoke to call YAP
> functions, so I tried linking directly to YAP, but in order to do that I
> need a .lib file to link against. I could not find it in the download, so I
> tried building YAP from the instructions given, only using VS2008 instead of
> VS 6.0. But every time I run that version, I get an error saying that I'm
> trying to access protected memory, and this happens with the first function
> I'm calling (YAP_FastInit).

I am actually impressed you can still build YAP with VC. I have been
building YAP with icc but on Linux, on Windows I alway run off to
mingw/cygwin. mingw should generate a lib file.

> Finally, I tried calling the YAP function directly using ::LoadLibrary(
> "yap.dll" ) and ::GetProcAddress( hLib, "YAP_FastInit"), but the program I
> wrote that does that (a simple console program in C++), simply crashes
> without any warning whatsoever when I try this.
> So, are there any ideas on how I can call YAP from a C# program?

It looked like your first approach was on the right track.

My apologies

Vitor

> Daníel
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>
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> Yap-users mailing list
> Yap-users@...
> https://lists.sourceforge.net/lists/listinfo/yap-users
>
>

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