Bill Roper (billroper) wrote,
Bill Roper
billroper

How I Learned To Stop Worrying And Love clone()

So I'm still working on porting my code from C++ to Java. I'm over the 40,000 line mark now, which is good, but there is still a lot of stuff left to port. I've been working through the Var class for several days and am nearing the 6000 line mark there. (It's a large and important class with many methods.) And as I work down through it, I run into many other classes that aren't completed where I either go "I'll fix that later" or "I should go fix that now".

So I needed to copy an object that held an array of other complex objects that held still more complex objects along with a metric ton of ordinary data. And I was about to swear and write yet another copy constructor (because I am a recalcitrant C++ programmer apparently) when I suddenly realized that I was about to do way too much work.

If I implement the Cloneable interface and the clone() method on these objects, then I get a free bitwise copy of everything that they contain. So for that object with a metric ton of ordinary data, I just call super.clone() and I have now copied the metric ton of ordinary data and only need to fix up and clone the complex objects that I want to have new copies of, since my intent is to do a deep copy when calling clone().

So I ran around and implemented all of the necessary clone functions for half a dozen classes.

And the code base got 47 lines longer. Instead of a whole lot more lines of mechanical copying which would have pumped up the line count, but not actually done any more work.

Oh.

OK. I guess I'm not yet too old to learn some new tricks. :)
Tags: c++, computers, java, musings, work
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