Re: The D Programming Language

"James Kanze" <>
14 Dec 2006 17:45:06 -0500
Niklas Matthies wrote:

On 2006-12-13 23:48, Andrei Alexandrescu (See Website For Email) wrote:

Niklas Matthies wrote:

Well, it depends what one considers "basic". It's possible in Java to
have the statement

   System.out.println("Hello, world!");

output "Suprise!" (or any other arbitrary string), by appropriate
preceding code.


I didn't know that! How is it possible?

Because string objects initialized from string literals are just
regular instances of the java.lang.String class, which is implemented
in plain Java (with the exception of its intern() method).

Got code?

Here you go:

You missed the best part:

    class Test
        public static void main(String[] args) throws Exception
            java.util.HashSet set = new java.util.HashSet();
            set.add("Hello, World!");


            set.add("Hello, World!");
            System.out.println(set); // prints "[Surprise!, Surprise!]"

    System.out.println( "Hello, World!" );
                            // Also prints "Surprise!"



It's nice to know that string literals aren't constants. (Sort
of reminds me of Fortran IV, where constants passed to a
function could be modified by the function, so a different
constant would be passed the next time. If you look at Niklas'
code, you'll also see how you can get things like:
    String s = "Hello, World!" ;
    s.lastIndexOf( 'H' )
throwing an ArrayIndexOutOfBoundsException.

Of course, this was also the case in the original C. Maybe Java
got its ideas about how a string literal should behave from
there. Thank goodness we've made some progress in this respect
in C++ (and in C90---even the C standards committee thought that
modifying constants was taking empowerment of the programmer a
bit too far).

James Kanze (GABI Software)
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