Code Generators or T4 Templates, are they really e

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 better more efficient way to build the code through generics and templating.

While I slightly agree with this statement above, I have not really found effective ways to build templates that can say for instance instantiate themselves. In otherwords I can never do :

return new T();

Additionally, if I want to generate code based on database values I have found that using Microsoft.SqlServer.Management.SMO in conjunction with T4 templates have been wonderful at generating mass amounts of code without having to copy / paste or use resharper.

Many of the problems I have found with Generics too is that to my shock there are a lot of developers who do not understand them. When I do examine generics for a solution, there are times where it gets complicated because C# states that you cannot do something that may seem logical in my mind.

What are your thoughts? Do you prefer to build a generator, or do you prefer to use generics? Also, how far can generics go? I know a decent amount about generics, but there are traps and pitfalls that I always run into that cause me to resort to a T4 template.

What is the more proper way to handle scenarios where you need a large amount of flexibility? Oh and as a bonus to this question, what are good resources on C# and Generics?

Answer 1

A good percentage of what is in Visual Studio 2010 would not be possible without code generation. Entity Framework would not be possible. The simple act of dragging and dropping a control onto a form would not be possible, nor would Linq. To say that code generation should not be used is strange as so many use it without even thinking about it.

Answer 2

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.

Answer 3

Code generation, like generics, templates, and other such shortcuts, is a powerful tool. And as with most powerful tools, it amplifies the capaility of its user for good and for evil - they can't be separated.

So if you understand your code generator thoroughly, anticipate everything it will produce, and why, and intend it to do so for valid reasons, then have at it. But don't use it (or any of the other technique) to get you past a place where you're not to sure where you're headed, or how to get there.

Some people think that, if you get your current problem solved and some behavior implemented, you're golden. It's not always obvious how much cruft and opaqueness you leave in your trail for the next developer (which might be yourself.)