David Hayen talks about the problem of using code generation at a large scale within software projects. The first use gives a lovely RAD hit, but over time you get more constrained and limited by the generated code. I always found this problem using any kind of data-n-drop data binding (although .NET 2.0 windows forms data binding seems almost flexible enough).

It is hard to get large scale code generation perfect - almost impossible in reality. I find using code generation at a smaller scale to actually raise the level of abstraction in code more useful. Languages such as Boo and Ruby have great syntax for defining mini domain specific languages to raise abstraction levels. Syntactic macros in Nemerle and Lisp are true compile-time code generators. The key to these methods is that the programmer has not lost the expressivity his language gives him. If a certain macro is not really fitting, you can always write out the code long-hand and refactor later if necessary.

Large scale code generation assumes software is smooth and regular. In the real-world we have to deal with special cases and, worse, changing requirements. Trying to make a code generation tool fit all of these requires it to be as expressive as a real programming language! Only now we are buried in stacks of XML config files and templates.

One area I do see a benefit for these quick-n-dirty code generators is in prototyping. You want to get something half-real in front of customers quickly to gather feedback. However, never be precious about your code. The best writing is re-writing! A lot of software hangs around for a lot longer than we expect, or even hope. It is probably best to make it as maintainable as humanly possible.

The fact that a magic tool generated thousands of lines of code for you doesn't stop them for existing. The more code that exists, more chance there is for something to be wrong. If your chosen programming language requires you to write reams of code to express something that you can conceptualise more simply, then I'm sorry you need a better language.