[tcljava-user] Porting Tcl_ObjSetVar2 Tcl C API Invocations to TclJava

[Brian B. (US) <Bri...@da...>]

Hello TclJava/Jtcl Community,

Thanks again for all the effort that has gone into the TclJava and JTcl projects!

**QUESTION**

Does TclJava/JTcl have an equivalent to Tcl_ObjSetVar2; documented here: https://www.tcl.tk/man/tcl/TclLib/SetVar.htm?

If not, how might I work around this limitation?

**CONTEXT OF QUESTION**

We're using JTcl 2.8.0 on Windows and Linux.

I'm porting some C code to Java.  In the C code, a TCL command that returns two different TclObject values:

1. TclString is returned as the command's result using Tcl_SetObjResult.
2. Tcl_NewByteArrayObj is returned in the "outargSomeByteArray" TCL command parameter using Tcl_ObjSetVar2.

Here's some of the C TCL command code I'm porting to TclJava...

--snip--
Tcl_CreateObjCommand( pInterp->interp, "read_string", cmd_read_string, (ClientData)pInterp, NULL );
--snip--

/////////////////////////////////////////////////////////////////////
// cmd_read_string
//
// TCL syntax is:
//    read_string outargSomeByteArray
// returns <returnCode> either "OK", "TIMEOUT", "OVERFLOW", "MAIL", "MAINT", or "UNKNOWN"
/////////////////////////////////////////////////////////////////////

int cmd_read_string( ClientData clientData, Tcl_Interp * interp, int objc, Tcl_Obj * CONST objv[] ) {

    // ------------- SNIPPED CODE THAT DOES SOMETHING --

    // return #1 command response
    switch( rc ) {
        case TCL_VALID_STRING:
            Tcl_SetObjResult( interp, Tcl_NewStringObj( "OK", -1 ) );
            break;
        case TCL_TIMEOUT:
            Tcl_SetObjResult( interp, Tcl_NewStringObj( "TIMEOUT", -1 ) );
            break;
        case TCL_OVERFLOW:
            Tcl_SetObjResult( interp, Tcl_NewStringObj( "OVERFLOW", -1 ) );
            break;
        case TCL_PENDING_MAIL:
            Tcl_SetObjResult( interp, Tcl_NewStringObj( "MAIL", -1 ) );
            break;
        case TCL_MAINT_MODE:
            Tcl_SetObjResult( interp, Tcl_NewStringObj( "MAINT", -1 ) );
            break;
        case TCL_PENDING_CMD:
            Tcl_SetObjResult( interp, Tcl_NewStringObj( "COMMAND", -1 ) );
            break;
        case TCL_PENDING_SYS_CALLBACK:
            Tcl_SetObjResult( interp, Tcl_NewStringObj( "SYS_CALLBACK", -1 ) );
            break;
        default:
            Tcl_SetObjResult( interp, Tcl_NewStringObj( "ERROR", -1 ) );
            break;
    }
    
    // return #2 outargSomeByteArray
    Tcl_ObjSetVar2( interp, objv[ 1 ], NULL, Tcl_NewByteArrayObj( (unsigned char *)someString, someStringLength ), 0);

    return( TCL_OK );
}

In the Java port, I've got code like...

class cmd_read_string implements tcl.lang.Command {

// --snip--

    @Override
    public void cmdProc(Interp interp, TclObject[] objv) throws TclException {

        // ------------- SNIPPED CODE THAT DOES SOMETHING --

        // return #1 command response
        switch (rc) {
            case DefineConstants.TCL_VALID_STRING:
                interp.setResult("OK");
                break;
            case DefineConstants.TCL_TIMEOUT:
                interp.setResult("TIMEOUT");
                break;
            case DefineConstants.TCL_OVERFLOW:
                interp.setResult("OVERFLOW");
                break;
            case DefineConstants.TCL_PENDING_MAIL:
                interp.setResult("MAIL");
                break;
            case DefineConstants.TCL_MAINT_MODE:
                interp.setResult("MAINT");
                break;
            case DefineConstants.TCL_PENDING_CMD:
                interp.setResult("COMMAND");
                break;
            case DefineConstants.TCL_PENDING_SYS_CALLBACK:
                interp.setResult("SYS_CALLBACK");
                break;
            default:
                interp.setResult("ERROR");
                break;
        }

        // return #2 outargSomeByteArray
        // How to port from C to TclJava?  I see there is a TclByteArray.newInstance for the Tcl_NewByteArrayObj 
        // but TclJava seems to lack Tcl_ObjSetVar2 support.
        // Tcl_ObjSetVar2( interp, objv[ 1 ], NULL, Tcl_NewByteArrayObj( (unsigned char *)someString, someStringLength ), 0);   

    }

}

Sincerely,
Brian Brooks
Sr Software Engineer
Duluth, GA 30096