EngineCallBacks.redirectCallBack
the call back function for handling writeto and appendto
Calling Sequence
Parameters
Description
Examples
String redirectCallBack( Object data, String name, boolean append ) throws MapleException
data
-
arbitrary data that was passed into the Engine constructor
name
filename that the user passed to writeto or appendto
append
true if the user called appendto
redirectCallBack is a member function of the com.maplesoft.openmaple.EngineCallBacks interface. It allows the Java OpenMaple programmer to redirect output when requested by a call to writeto or appendto.
Output must be redirected to a file called name. If name is the NULL string, then the current redirection, if any, must be terminated. All subsequent output must be directed to the original location.
The append parameter is true if the user called appendto, otherwise it is false.
import com.maplesoft.openmaple.*;
import com.maplesoft.externalcall.MapleException;
class Example
{
static private class CallBacks implements EngineCallBacks
boolean limitExceeded;
CallBacks()
limitExceeded = false;
}
public void textCallBack( Object data, int tag, String output )
throws MapleException
switch ( tag )
case MAPLE_TEXT_OUTPUT:
System.out.print( "Text: " );
break;
case MAPLE_TEXT_DIAG:
System.out.print( "Diag: " );
case MAPLE_TEXT_MISC:
System.out.print( "Misc: " );
case MAPLE_TEXT_HELP:
System.out.print( "Help: " );
case MAPLE_TEXT_QUIT:
System.out.print( "Quit: " );
case MAPLE_TEXT_WARNING:
System.out.print( "Warning: " );
case MAPLE_TEXT_DEBUG:
System.out.print( "Debug: " );
System.out.println( output );
public void errorCallBack( Object data, int offset, String msg )
if ( offset >= 0 )
throw new MapleException( "Error: "+msg );
else
throw new MapleException( "syntax error at offset "+offset+
": "+msg );
public void statusCallBack( Object data, long kbused, long kballoced,
double timeused )
if ( timeused > 5 )
limitExceeded = true;
System.out.println( "Status: used = "+kbused+", alloced = "+
kballoced+", time = "+timeused );
public String readLineCallBack( Object data, boolean debug )
return "readline";
public boolean redirectCallBack( Object data, String output, boolean
append )
System.out.println( "redirect to "+output+" append = "+append );
return true;
public String callBackCallBack( Object data, String output )
System.out.println( "callback: "+output );
return output+";";
public boolean queryInterrupt( Object data )
return limitExceeded;
public String streamCallBack( Object data, String name, String args[] )
StringBuffer sbuf;
int i;
sbuf = new StringBuffer( name );
for ( i = 0; i < args.length; i++ )
sbuf.append( args[i] );
return sbuf.toString();
public static void main( String notused[] ) throws MapleException
String mapleArgs[];
Engine engine;
MString s;
mapleArgs = new String[1];
mapleArgs[0] = "java";
engine = new Engine( mapleArgs, new CallBacks(), null, null );
engine.evaluate( "writeto( \dummyfile1\ ):" );
engine.evaluate( "appendto( \dummyfile2\ ):" );
engine.evaluate( "writeto( terminal ):" );
Executing this code produces the following output.
redirect to dummyfile1 append = false
redirect to dummyfile2 append = true
redirect to null append = false
See Also
ExternalCalling/Java/MapleException
OpenMaple
OpenMaple/Java/Engine
OpenMaple/Java/Engine/Engine
OpenMaple/Java/EngineCallBacks
OpenMaple/Java/EngineCallBacksDefault
OpenMaple/Java/EngineCallBacksDefault/redirectCallBack
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