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digitalmars.D.bugs - [Issue 6046] New: Not true for Java about Function Hijacking.

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6046

           Summary: Not true for Java about Function Hijacking.
           Product: D
           Version: unspecified
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: websites
        AssignedTo: nobody puremagic.com
        ReportedBy: ongbp yahoo.com


--- Comment #0 from Matthew Ong <ongbp yahoo.com> 2011-05-23 02:45:48 PDT ---
Hi Digitalmars/Walter Bright,


http://www.digitalmars.com/d/2.0/hijack.html

This talk covers function hijacking, where adding innocent and reasonable
declarations in a module can wreak arbitrary havoc on an application program in
C++(maybe true) and Java(not true).

Since I have not done C++ for a long while, I am not going to comment about
that. But Java I have to place this request for correction from DigitalMars.

javac(from sun) Compiler will complain if there is an ambiguous to link any
indentifier that has the same signature for contructor,
methods(static/overloaded/overriden)

Overload Sets
Java denys global functions. All functions/methods are within a single class.
Within the same class, the overloaded methods cannot have the same signature.

public class MyClass{

public int myVal(){
}

public String myVal(){ // compiler will complain here as error and NOT warning.
}
}

Both the method identifier and zero param list makes a identical signature.

Derived Class Member Function Hijacking
IDE like Netbeans and does flag:

 override
public void myMethodA(){ // Say you did not use the override tag
}



Base Class Member Function Hijacking
to prevent the child class from stealing your implementation for this single
method, do:

public final void myMethodA(){ // final == sealed in C#
}


That is shown clearly when you tries to import both this 2 classes within Java:
import java.util.Date;
import java.sql.Date;

public class MyTest{
    public static void main(String[] args){
         Date now=new Date(); // thinking that you are using java.util.Date;
    }
}


Again, as a senior Java Developer since java jdk 1.1 I agrees D as a good
replacement for C++ because of modern design and approaches.

Kindly correct that to avoid confusing the new Java to D developer.

There are also other run time intelligent build into JVM to avoid malicious
hacker attack on such thing using class proxy & stub.

-- 
Matthew Ong
email: ongbp yahoo.com

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6046


Steven Schveighoffer <schveiguy yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |schveiguy yahoo.com


--- Comment #1 from Steven Schveighoffer <schveiguy yahoo.com> 2011-05-23
04:40:59 PDT ---
I would say the only valid request here is to mention that Java has the
 override flag which can be used to prevent hijacking, but is not the default.

I think you misunderstood the point of this article.  The point is to prevent
hijacking the *default* must be to prevent hijacking.  Having annotations and
modifiers that allow you to prevent hijacking is not good enough.

I think you also misunderstood the scope in the article of Java's shortcomings.
 I think the author only singles out one aspect of Java, it's overload
resolution for inherited methods.  Nothing else applies to Java.

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prev sibling parent d-bugmail puremagic.com writes:
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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla digitalmars.com
         Resolution|                            |INVALID


--- Comment #2 from Walter Bright <bugzilla digitalmars.com> 2012-01-20
22:12:16 PST ---
I agree with Steven.

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