Re: AspectJ: solution to Java's repetitiveness?
jhc0033@gmail.com wrote:
On Apr 19, 8:05 pm, Mark Space <marksp...@sbc.global.net> wrote:
Even C++ creates copy constructors with this semantics for you.
Er, that's what Java's .clone() method does by default.
I'm afraid it doesn't have the right semantics. I wrote a test
application to check this. Suppose I want a tree of 3D vectors. I also
want to be able to copy these trees so that I can modify the original
with impunity:
I also wrote a test program to try to address part of your toString() issue.
However, Java doesn't allow me to access non-public fields the way I
wanted. So it wasn't useful, as it would require even more boilerplate.
The failed test is below. There's a small formatting error, and there's
no attempt to deal with inheritance, because the one case I had failed
in such a way that I didn't see any way to proceed.
Maybe someone else can see what I'm attempting to do and suggest
improvements?
The values or ways I initialize the classes just give the classes random
values for the toString method to work on, btw. The field values are not
significant at all.
package tostringtest;
import java.lang.reflect.Field;
public class Main
{
public static void main( String[] args )
{
System.out.println( new TestBase( 10, "Hello" ) );
System.out.println( new TestChild( 11.11f, 'b' ) );
}
}
class TestBase
{
private int field1;
private String myString;
public TestBase( int field1, String myString )
{
this.field1 = field1;
this.myString = myString;
}
@Override
public String toString()
{
StringBuilder sb = new StringBuilder();
sb.append( '[' );
sb.append( this.getClass().getSimpleName() );
sb.append( ": " );
for ( Field f : this.getClass().getDeclaredFields() )
{
sb.append( f.getName() );
sb.append( ": " );
try
{
sb.append( f.get( this ).toString() );
}
catch ( IllegalArgumentException ex )
{
sb.append( ex.toString() );
}
catch ( IllegalAccessException ex )
{
sb.append( ex.toString() );
}
sb.append( ", " );
}
sb.append( ']' );
return sb.toString();
}
}
class TestChild extends TestBase
{
private float ftest;
private char ctest;
public TestChild( float ftest, char ctest )
{
super( (int)ftest, Character.toString( ctest ) );
this.ftest = ftest;
this.ctest = ctest;
}
}
This fails with an exception when trying to access the child classes
fields from the base class, of course.
run:
[TestBase: field1: 10, myString: Hello, ]
[TestChild: ftest: java.lang.IllegalAccessException: Class
tostringtest.TestBase can not access a member of class
tostringtest.TestChild with modifiers "private", ctest:
java.lang.IllegalAccessException: Class tostringtest.TestBase can not
access a member of class tostringtest.TestChild with modifiers "private", ]
BUILD SUCCESSFUL (total time: 0 seconds)