Code Generators or T4 Templates, are they really evil?

Question

I have heard people state that Code Generators and T4 templates should not be used. The logic behind that is that if you are generating code with a generator then there is a bet

Answer 1

Generics and code generation are two different things. In some cases you could use generics instead of code generation and for those I believe you should. For the other cases code generation is a powerful tool.

For all the cases where you simply need to generate code based on some data input, code generation is the way to go. The most obvious, but by no means the only example is the forms editor in Visual Studio. Here the input is the designer data and the output is the code. In this case generics is really no help at all, but it is very nice that VS simply generates the code based on the GUI layout.

Answer 2

Code generation is for me a workaround for many problems found in language, frameworks, etc. They are not evil by themselves, I would say it is very very bad (i.e. evil) to release a language (C#) and framework which forces you to copy&paste (swap on properties, events triggering, lack of macros) or use magical numbers (wpf binding).

So, I cry, but I use them, because I have to.

Answer 3

Code generators could be considered a code smell that indicate a flaw or lack of functionality in the target langauge.

For example, while it has been said here that "Objects that persist can not be generalized", it would be better to think of it as "Objects in C# that automatically persist their data can not be generalized in C#", because I surely can in Python through the use of various methods.

The Python approach could, however, be emulated in static languages through the use of operator[ ](method_name as string), which either returns a functor or a string, depending on requirements. Unfortunately that solution is not always applicable, and returning a functor can be inconvenient.

The point I am making is that code generators indicate a flaw in a chosen language that are addressed by providing a more convenient specialised syntax for the specific problem at hand.