Expose X# run-time functions to C#

[Jamal]

I am opening a dbf using the DBFCDX driver, but it fails to open CDX file since it contains functions such as DTos().

How to add the entire set of the X# run-time function in C# and also create my BYO functions so that CDX can link to them successfully.

I created a C# function:

Code: Select all

public string DToS(XSharp.__Date dDate)
        {
            return Dbf.DToS(dDate);
            
        }	

but I call Dbf.DbUseArea(...), I get $exception {"Specified cast is not valid."} XSharp.Error

Note: the DBF file opens using the DBFNTX driver.

Please advise.

Thanks!
Jamal

[wriedmann]

Hi Jamal,
you need to build your own intermediate DLL that uses the X# runtime and exposes only strongly typed methods.
I'm doing something like that to use DBFs in my X# Core applications (that don't use the X# runtime itself).
Wolfgang

[Chris]

Hi Jamal,

Did you add references to the XSharp runtime dlls? If you did, then the macro compiler should find them automatically.

I just tried the following and it seems to work fine, I get the first logical record printed:

Code: Select all

public class Program
{
	static void Main()
	{
		string cPath;
		cPath = "c:...testcs.dbf";
		XSharp.RT.Functions.VoDbUseArea(true, "DBFCDX" , cPath , "alias" , true , false);
		XSharp.RT.Functions.DbGoTop();
		System.Console.WriteLine(XSharp.RT.Functions.FieldGet(1).ToString());
		XSharp.RT.Functions.VoDbCloseArea();		
	}
}

[Chris]

Also, when you want to use in the dbf indexes (or in the macro compiler in gnerl) methods defined in your c# module, you need to put them in a class and add this assembly wide attribute:

[assembly: XSharp.Internal.ClassLibrary("MyRuntimeFuncsClass", "")]

Wolfgang, what you say is correct for directly calling X# runtime functions that have CLIPPER calling convention from c#, but when using the macrocompiler (so also functions in expressions) this is not a problem, because the macro compiler know how to call them.

[Jamal]

Hi Chris,

I am still getting the "Specified cast is not valid." error when calling XSharp.RT.Functions.DbUseArea().

Could you please test the attached dbf file and cdx?

Note: the CDX has one order on DToS(HIREDDATE). In X# the DBF file opens fine.

Jamal

[Jamal]

It seems adding the following line:

XSharp.CoreDb.RddInfo(_SET_AUTOORDER, 1);

was causing the error. After I commented it out, the file opened fine!

I tested also in X#, and got the same error:

Code: Select all

PRIVATE METHOD OpenDBFButton_Click(sender AS OBJECT, e AS System.EventArgs) AS VOID STRICT
             RddInfo(_SET_AUTOOPEN, true)
           
            RddInfo(_SET_AUTOORDER, 1)   // causes Specified cast is not valid. This works in VO.
            
            if (DbUseArea(true, "DBFCDX", "C:TestingDirTESTDBF.dbf", "TESTDBF", true, false))
                MessageBox.Show(LastRec().ToString())
                DBCloseArea()
                MessageBox.Show("Opened")
                
            else
                MessageBox.Show("Failed") 
            endif
            RETURN

[Chris]

Thanks Jamal, problem confirmed and logged!

[wriedmann]

Hi Chris,

Wolfgang, what you say is correct for directly calling X# runtime functions that have CLIPPER calling convention from c#, but when using the macrocompiler (so also functions in expressions) this is not a problem, because the macro compiler know how to call them.

I have a few classes in my XbaseInterface DLL:
- an AppDBServer class that inherits from the DBServer class
- a CoreDBFServer class that acts as proxy for the AppDBServer class and exposes methods like FieldGetString(), FieldGetLogic(), FieldGetDecimal() and a few more so I don't need to cast the return values in my Core dialec applications
- a XbDate class that works like a Nullable<DateTime>, but maintains only the date part. It is like the Xbase date, but usable without problems in Core dialect applications.

If there is some interest, I can share that library toghether with a sample.

Wolfgang

[Juraj]

Hi Wolfgang,


I create the new app only as WPF in Core dialect. Sometimes I need to load an older DBF file. Your library would help.

Juraj

[Jamal]

Hi Wolfgang,

That would be awesome!

Jamal