I've been having a little trouble with implementing traces for the widget
variables used in my Swank package (a Tk-like interface to Swing). Below is
some example Java code that implements a trace on a variable (in this case
for a textual widget, like an entry). The code works fine until you try to
use it from a Tcl proc where you use an "upvar" command..
For example, if you test with the following procedure and commands:
proc testtrace {varnm value} {
upvar #0 $varnm panvar
set panvar(name) $value
}
entry .e -textvariable tvar(name)
testtrace tvar value
you find that the arguments string1 and string2 of traceProc are "panvar"
and "name"
not "tvar" and "name" and an exception is thrown:
can't set panvar(name): can't read "panvar(name)" no such variable
Any thoughts?
Bruce
package swank;
import java.util.*;
import java.lang.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.event.*;
import tcl.lang.*;
public class myDocumentListener implements DocumentListener,VarTrace
{
Interp interp;
String varName = null;
JTextComponent jtext;
boolean traceLock = false;
myDocumentListener(Interp interp,JTextComponent jtext) {
this.interp = interp;
this.jtext = jtext;
}
public void traceProc(Interp interp, String string1, String string2, int
flags) throws TclException
{
if (!traceLock) {
TclObject tobj = interp.getVar(string1,string2,TCL.GLOBAL_ONLY);
jtext.setText(tobj.toString());
}
traceLock = false;
}
public void setVarName(String name) throws TclException {
if ((varName != null) && (!varName.equals(""))) {
interp.untraceVar(varName,this,TCL.TRACE_WRITES|
TCL.GLOBAL_ONLY);
}
try {
TclObject tobj = interp.getVar(name,TCL.GLOBAL_ONLY);
}
catch (TclException tclException)
{
TclObject tobj = TclString.newInstance("");
interp.setVar(name,tobj,TCL.GLOBAL_ONLY);
}
interp.traceVar(name,this,TCL.TRACE_WRITES| TCL.GLOBAL_ONLY);
varName = new String(name);
}
public String getVarName() {
return(varName);
}
public void updateVar(DocumentEvent docEvent)
{
if (varName==null) {
return;
}
Document doc = docEvent.getDocument();
String string=null;
try {
string = doc.getText(0,doc.getLength());
}
catch (BadLocationException e) {
return;
}
TclObject tobj = TclString.newInstance(string);
try {
traceLock = true;
interp.setVar(varName,tobj,TCL.GLOBAL_ONLY);
} catch (TclException tclException) {
return;
}
}
public void insertUpdate(DocumentEvent docEvent) {
updateVar(docEvent);
}
public void removeUpdate(DocumentEvent docEvent) {
updateVar(docEvent);
}
public void changedUpdate(DocumentEvent docEvent) {
updateVar(docEvent);
}
}
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