Mastering Rust - Second Edition

Built-in macros in the standard library

Apart from println!, there are other useful macros in the standard library that are implemented using the macro_rules! macro. Knowing about them will help us appreciate the places and situations where using a macro is a cleaner solution, while not sacrificing readability.

Some of these macros are as follows:

• dbg!: This allows you to print the value of expressions with their values. This macro moves whatever is passed to it, so if you only want to give read access to their types, you need to pass a reference to this macro instead. It's quite handy as a tracing macro for expressions during runtime.
• compile_error!: This macro can be used to report an error from code at compile time. This is a handy macro ...