Do! When the need arises. Language designers wouldn't include such facilities if there was never a need. Ruby is hardly alone in this. I can't imagine a Lisper

Do! When the need arises. Language designers wouldn't include such facilities if there was never a need. Ruby is hardly alone in this. I can't imagine a Lisper ever saying never use macros. C++ has templates, Rust has macros, Python has magic methods, metaclasses and decorators. Javascript, Java, Perl, C let you do some pretty horrific stuff because sometimes you need the the flexibility. If you look at enough library and framework code, you will see those things in use. Don't! Be dogmatic about programming. There are always use cases.