Re: AspectJ: solution to Java's repetitiveness?

From:
=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 20 Apr 2008 23:33:38 -0400
Message-ID:
<480c0b0c$0$90274$14726298@news.sunsite.dk>
Mark Space wrote:

EricF wrote:

AspectJ will not address those issues. It's best for cross-cutting
concerns, code that might be common across methods - logging, timing,
and transactions are frequent examples.


I've never worked with any type of aspect oriented programming, although
I've seen it described. At first blush I would have thought that it
might address the OP's needs.

So, when you wave code, are you weaving static methods? Or does the
code you weave in have access to a "this" pointer?

Because if "this" is accessible that could allow some pretty substantial
and useful stuff. If it's just static methods, then I guess it would be
pretty limited.


I just read a bit about AspectJ and introductions.

Yes - AspectJ can add this kind of functionality.

Example:

package test;

public interface AutoToString {
     String toString();
}

and

package test;

import java.lang.reflect.*;

public aspect AutoToStringImpl {
     declare parents: test.* implements AutoToString;
     public String AutoToString.toString() {
         try {
             StringBuilder sb = new StringBuilder();
             Method[] m = getClass().getMethods();
             for(int i = 0; i < m.length; i++) {
                 if(m[i].getName().startsWith("get") &&
m[i].getDeclaringClass() == getClass()) {
                     if(i > 0) {
                         sb.append(",");
                     }
                     sb.append(m[i].invoke(this, new Object[0]));
                 }
             }
             return sb.toString();
         } catch(IllegalAccessException e) {
             return "Ooops";
         } catch(InvocationTargetException e) {
             return "Ooops";
         }
     }
}

Arne

PS: No - I don't think many will want to use this code.

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