Tuesday, August 11, 2009

Software Factories are Evil

I started this post a loooong time ago.

A resent pod cast on .net Rocks and an article in version2.dk reminded me of what I wanted to write.

I think code generation is a sign of bad design. Code generation is a sign of a need for repetitive code. Repeating code is the certain path to errors.

The worst kind is the one where you are supposed to edit some of the resulting code. The purpose of the process is to let you specify something in an abstract manner and have the details of the system taken care of by the generator. Once you edit the code you brake the abstraction and you will no longer be able to make changes to your application using the high abstraction. Examples of this could be the Windows Forms editor in visual studio. When you drag components on to your form, a lot of code is generated behind the scene. If you have to change anything in the generated code you might loose it later if some components are moved around on the design surface.

Another way of generating code is to generate static code that doesn't need to be changed by the user. This can be done to create a structure that the user can utilize in his/her program. I'm suggesting that you avoid this as well if possible. The bad impact on your program is not as big as on the previous method though. The reason for applying this could be to work as a shortcut to make something compile together.
An example of this could be the designer file for aspx files in visual studio. When visual studio parses an aspx file an C# file is created so it can be compiled as part of a C# project. The problem with this file is that it adds no new information to the project, but adds complexity in terms of extra files. Once in a while this file will be out of sync and you have to restart visual studio.

Initializing an object migth be so compex that you need a sniplet to assist you every time. If this is the case you should create a simpler way to initialize your object rather than create a sniplet for it.

My recomendation is therefore that if you are in need of code generation in your project you should reconsider your application design.

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