Not GP, but for instance, Python web frameworks are oriented around decorators, and Rust web frameworks are oriented around macros. The syntax looks pretty similar, but like GP says, in dynamic languages you're using a (higher order) function, and in static languages you're using code generation for the same purpose.

I am confused. "Code gen" is a fuzzy concept once you have a virtual machine because you can do it at runtime. This is how mocking works in Java and C#. What you describe already exists in Java and C# -- decorators for web frameworks. I would not describe Java nor C# as dynamic. I describe them as "stricter" (types) and Python as "weaker" (types). To quote Norman Ramsey: "Every time I see a question about "strong" or "weak" typing, I kill a kitten." :-)