error[E0615]: attempted to take value of method `speak` on type `Cat` --> $DIR/assign-to-method.rs:22:10 | LL | nyan.speak = || println!("meow"); | ^^^^^ method, not a field | = help: methods are immutable and cannot be assigned to error[E0615]: attempted to take value of method `speak` on type `Cat` --> $DIR/assign-to-method.rs:23:10 | LL | nyan.speak += || println!("meow"); | ^^^^^ method, not a field | = help: methods are immutable and cannot be assigned to error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0615`.