Registered: Apr, 2005
Re: Have Generics Killed Java?
Posted: Jul 24, 2010 10:25 AM
> > Many dynamic languages let you dynamically add methods
> > to an object. Really nice for quickly hacking
> > existing code, but a maintenance nightmare, because now
> > functional contracts are also gone, forcing a developer
> > to understand the full codebase to know which part of an
> > object's functionality is available at runtime.
> Yeah. It's a dual edge sword, especially if it's done
> willy-nilly, anywhere in the code. But best practices
> suggest doing such things as close to "up front" as is
> With modules, such things are nicely encapsulated, too. So
> if one module needs an extension to String, and another
> module needs a different extension, each is free to add
> the extension it needs.
> I understand the potential danger. But there is really no
> substitute. When I'm knee deep in code and find that I
> really *need* some feature the designers left out of the
> original class, it's just not practical to subclass
> String, rewrite every method to use the Subclass, and
> modify every API to recast incoming and outgoing Strings.
> (I know. I can hear you shuddering. But I love open
> classes. But then, I have become a big fan of writing
> readable, runnable tests before writing code.)
I'm not sure I understand the issue here. I take it the "subclass String and add your extension" is meant as a strawman. Every programmer I know would write a StringHelper class with a static method that takes a String and provides the functionality.
However, Ruby monkey patching, C# extension methods, C++'s nonfriend free functions, Java static methods in different classes that take the object (eg., the StringHelper class), and similar mechanisms really are syntactic sugar for the same thing: a method that takes an object and does stuff with it. I have a hard time seeing any mechanism as inherently better than the others so long as the code organization doesn't get squirrelly.