No, the advice is good. If the wrong function was called, or a function is called with the wrong input, it’s just a bug and no amount of ‘validations’ can fix i

No, the advice is good. If the wrong function was called, or a function is called with the wrong input, it’s just a bug and no amount of ‘validations’ can fix it. The article is written in the context of Rust, which has a type system, so the compiler can help check. In cases where a function’s precondition can’t be expressed in the type system, the function should check at the start and bale. For example, it’s reasonable in Java to check if parameters are null (since the compiler cannot do this). For more on this, Google “parse, don’t validate”.