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

[Tom P. <tpo...@ny...>]

Hi Brian,

JTcl uses Java method overloading for most of the different
combinations of Inter.setVar() for setting by varname as String
or TclObject with a value of String or TclObject.

See all of the various method signatures for Interp.setVar().  Same
goes for Interp.setResult(), overloaded for a few primitive types,
String, and TclObject.

http://jtcl-project.github.io/jtcl/apidocs/tcl/lang/Interp.html

-Tom


On Fri, Jun 03, 2016 at 02:29:15PM +0000, Brian Brooks (US) wrote:
> 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
> 
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-- 
Tom Poindexter
tpo...@ny...