tcljava-user

[tcljava-user] How to use Interp.setResult?

[Bret C. W. <bc...@ya...>]

Hello,

I have not found good documentation for some of Jacl - the API docs on
the tcljava.sourceforge.net site are not giving me a good enough
understanding to determine how to solve an exception.

I have a command-line java program.  In it's primary class constructor,
it creates a TCL Interp session with the name of an external script
file, and exits when the Interp session is complete.  In response to
various commands found in a script, various Java objects are created,
and methods called on those objects from the script.  I have a number of
working examples of this, including some that successfully return values
to the Interp session for further processing.

But I haven't figured out what Interp.setResult() does, and it looks as
if it might be useful.  Consider these two methods.  The first
(getColumnCount) works as expected, and I can access the return value in
my script.  The second (getEntry) always provokes the exception listed
below.  'myInterp' was set with a reference to the (one-and-only) Interp
session when the object these methods belong to was created and is valid
for the entire time.

Please don't tell me to read the docs, I have and have tried many
experiments and they don't tell me what circumstance to use the
Interp.setResult() method in or what might be the problem here.

Thanks in advance,
bcw

TCL:
$tableName getEntry $column $row

Java:
      /**
       * *@return* int - The number of columns in this result set.
       */
      *public* *int* getColumnCount()
            {
            log.debug( "getColumnCount - columnCount is " + columnCount );
            *return* columnCount;
            }
 
      *public* *void* getEntry( String columnName, *int* currentRow )
*throws* TclException
            {
            log.debug( "getEntry - column name is " + columnName );
            myInterp.setResult( "an Answer" );
            }
 
 
tcl.lang.ReflectException
            at tcl.lang.JavaInvoke.call(JavaInvoke.java:328)
            at tcl.lang.JavaInvoke.callMethod(JavaInvoke.java:161)
            at tcl.lang.ReflectObject.cmdProc(ReflectObject.java:916)
            at tcl.lang.Parser.evalObjv(Parser.java:826)
            at tcl.lang.Parser.eval2(Parser.java:1228)
            at tcl.lang.Parser.evalTokens(Parser.java:1008)
            at tcl.lang.Parser.eval2(Parser.java:1215)
            at tcl.lang.Procedure.cmdProc(Procedure.java:174)
            at tcl.lang.Parser.evalObjv(Parser.java:826)
            at tcl.lang.Parser.eval2(Parser.java:1228)
            at tcl.lang.Parser.evalTokens(Parser.java:1008)
            at tcl.lang.Parser.eval2(Parser.java:1215)
            at tcl.lang.Interp.eval(Interp.java:2679)
            at tcl.lang.Interp.eval(Interp.java:2747)
            at tcl.lang.IfCmd.cmdProc(IfCmd.java:64)
            at tcl.lang.Parser.evalObjv(Parser.java:826)
            at tcl.lang.Parser.eval2(Parser.java:1228)
            at tcl.lang.Interp.eval(Interp.java:2679)
            at tcl.lang.Interp.eval(Interp.java:2747)
            at tcl.lang.ForeachCmd.cmdProc(ForeachCmd.java:98)
            at tcl.lang.Parser.evalObjv(Parser.java:826)
            at tcl.lang.Parser.eval2(Parser.java:1228)
            at tcl.lang.Interp.eval(Interp.java:2679)
            at tcl.lang.Interp.eval(Interp.java:2747)
            at tcl.lang.WhileCmd.cmdProc(WhileCmd.java:43)
            at tcl.lang.AutoloadStub.cmdProc(Extension.java:119)
            at tcl.lang.Parser.evalObjv(Parser.java:826)
            at tcl.lang.Parser.eval2(Parser.java:1228)
            at tcl.lang.Procedure.cmdProc(Procedure.java:174)
            at tcl.lang.Parser.evalObjv(Parser.java:826)
            at tcl.lang.Parser.eval2(Parser.java:1228)
            at tcl.lang.Parser.evalTokens(Parser.java:1008)
            at tcl.lang.Parser.eval2(Parser.java:1215)
            at tcl.lang.Interp.eval(Interp.java:2679)
            at tcl.lang.Interp.evalFile(Interp.java:2940)
            at
com.ssg.dataconverter.DataConverter.<init>(DataConverter.java:76)
            at
com.ssg.dataconverter.DataConverter.main(DataConverter.java:159)

Re: [tcljava-user] How to use Interp.setResult?

[Mo D. <mo...@mo...>]

Bret Comstock Waldow wrote:
> Hello,
>
> I have not found good documentation for some of Jacl - the API docs on
> the tcljava.sourceforge.net site are not giving me a good enough
> understanding to determine how to solve an exception.
>
> I have a command-line java program.  In it's primary class constructor,
> it creates a TCL Interp session with the name of an external script
> file, and exits when the Interp session is complete.  In response to
> various commands found in a script, various Java objects are created,
> and methods called on those objects from the script.  I have a number of
> working examples of this, including some that successfully return values
> to the Interp session for further processing.
>
> But I haven't figured out what Interp.setResult() does, and it looks as
> if it might be useful.
The setResult() method sets the "result" pointer in a Jacl interpreter 
to a specific TclObject. It is typically
used from a Java implementation of a Tcl method to indicate the result 
of a Tcl command. If you have
a Java method, it is better to just have it return a Java result and 
then invoke the method with the java::call
command or from a class instance handle (like java0x1, a result object 
from a java::new command).
> TCL:
> $tableName getEntry $column $row
>
> Java:
>       /**
>        * *@return* int - The number of columns in this result set.
>        */
>       *public* *int* getColumnCount()
>             {
>             log.debug( "getColumnCount - columnCount is " + columnCount );
>             *return* columnCount;
>             }
>  
>       *public* *void* getEntry( String columnName, *int* currentRow )
> *throws* TclException
>             {
>             log.debug( "getEntry - column name is " + columnName );
>             myInterp.setResult( "an Answer" );
>             }
>  
>  
> tcl.lang.ReflectException
>             at tcl.lang.JavaInvoke.call(JavaInvoke.java:328)
>             at tcl.lang.JavaInvoke.callMethod(JavaInvoke.java:161)
>             at tcl.lang.ReflectObject.cmdProc(ReflectObject.java:916)
>   
It is not clear what if going on from this example code and stack trace. 
Typically, the ReflectException means there
was some error in the Java code and it got wrapped into a 
ReflectException when moving from Java back to tcl.

When Jacl hits a ReflectException, it saves the original Java exception 
object and a description string are saved
in the global variable named "errorCode". Printing out a stace trace of 
the Java exception found there would likely
be a good place to start.

Mo DeJong