Enumerations

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Enums1.rs

#![allow(dead_code)]
#![allow(non_snake_case)]
#![allow(non_upper_case_globals)]
#[macro_use]
mod utils;
use num_enum::IntoPrimitive;
use num_enum::TryFromPrimitive;

enum_str! {
enum CompassPoint {
	North = 0,
	East = 1,
	South = 2,
	West = 3,
}
}

fn compass_point_to_string(c:CompassPoint) -> String {
	let mut result:&'static str = "";
	match c {
		CompassPoint::North => {
			result = "North";
		}
		CompassPoint::East => {
			result = "East";
		}
		CompassPoint::South => {
			result = "South";
		}
		CompassPoint::West => {
			result = "West";
		}
	}
	return result.to_string();
}

fn turn_right(c:CompassPoint) -> CompassPoint {
	if c == CompassPoint::North {
		return CompassPoint::East;
	} else if c == CompassPoint::East {
		return CompassPoint::South;
	} else if c == CompassPoint::South {
		return CompassPoint::West;
	} else {
		return CompassPoint::North;
	}
}

fn main() {
	let mut cp1:CompassPoint = CompassPoint::North;
	println!("cp1: {}", cp1.name());
	println!("SOUTH: {}", compass_point_to_string(CompassPoint::South));
	println!("turnRight(cp1): {}", compass_point_to_string(turn_right(cp1)));
	let cp2:CompassPoint = CompassPoint::East;
	if cp1 == cp2 {
		println!("cp1 == cp2");
	} else {
		println!("cp1 != cp2");
	}
	cp1 = cp2;
	if cp1 == cp2 {
		println!("cp1 == cp2");
	} else {
		println!("cp1 != cp2");
	}
}

Output

$ rustc Enums1.rs error[E0308]: mismatched types --> Enums1.rs:26:9 | 10 | fn CompassPointToString(c:CompassPoint) -> String { | ------ expected `String` because of return type ... 26 | return result; | ^^^^^^- help: try using a conversion method: `.to_string()` | | | expected `String`, found `&str` error[E0369]: binary operation `==` cannot be applied to type `CompassPoint` --> Enums1.rs:30:7 | 30 | if c == CompassPoint::NORTH { | - ^^ ------------------- CompassPoint | | | CompassPoint | note: an implementation of `PartialEq` might be missing for `CompassPoint` --> Enums1.rs:3:1 | 3 | enum CompassPoint { | ^^^^^^^^^^^^^^^^^ must implement `PartialEq` help: consider annotating `CompassPoint` with `#[derive(PartialEq)]` | 3 + #[derive(PartialEq)] 4 | enum CompassPoint { | error[E0369]: binary operation `==` cannot be applied to type `CompassPoint` --> Enums1.rs:32:14 | 32 | } else if c == CompassPoint::EAST { | - ^^ ------------------ CompassPoint | | | CompassPoint | note: an implementation of `PartialEq` might be missing for `CompassPoint` --> Enums1.rs:3:1 | 3 | enum CompassPoint { | ^^^^^^^^^^^^^^^^^ must implement `PartialEq` help: consider annotating `CompassPoint` with `#[derive(PartialEq)]` | 3 + #[derive(PartialEq)] 4 | enum CompassPoint { | error[E0369]: binary operation `==` cannot be applied to type `CompassPoint` --> Enums1.rs:34:14 | 34 | } else if c == CompassPoint::SOUTH { | - ^^ ------------------- CompassPoint | | | CompassPoint | note: an implementation of `PartialEq` might be missing for `CompassPoint` --> Enums1.rs:3:1 | 3 | enum CompassPoint { | ^^^^^^^^^^^^^^^^^ must implement `PartialEq` help: consider annotating `CompassPoint` with `#[derive(PartialEq)]` | 3 + #[derive(PartialEq)] 4 | enum CompassPoint { | error[E0277]: `CompassPoint` doesn't implement `std::fmt::Display` --> Enums1.rs:43:22 | 43 | println!("cp1: {}", cp1); | ^^^ `CompassPoint` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `CompassPoint` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0369]: binary operation `==` cannot be applied to type `CompassPoint` --> Enums1.rs:47:9 | 47 | if cp1 == cp2 { | --- ^^ --- CompassPoint | | | CompassPoint | note: an implementation of `PartialEq` might be missing for `CompassPoint` --> Enums1.rs:3:1 | 3 | enum CompassPoint { | ^^^^^^^^^^^^^^^^^ must implement `PartialEq` help: consider annotating `CompassPoint` with `#[derive(PartialEq)]` | 3 + #[derive(PartialEq)] 4 | enum CompassPoint { | error[E0369]: binary operation `==` cannot be applied to type `CompassPoint` --> Enums1.rs:53:9 | 53 | if cp1 == cp2 { | --- ^^ --- CompassPoint | | | CompassPoint | note: an implementation of `PartialEq` might be missing for `CompassPoint` --> Enums1.rs:3:1 | 3 | enum CompassPoint { | ^^^^^^^^^^^^^^^^^ must implement `PartialEq` help: consider annotating `CompassPoint` with `#[derive(PartialEq)]` | 3 + #[derive(PartialEq)] 4 | enum CompassPoint { | error: aborting due to 7 previous errors Some errors have detailed explanations: E0277, E0308, E0369. For more information about an error, try `rustc --explain E0277`.

Enums2.rs

#![allow(dead_code)]
#![allow(non_snake_case)]
#![allow(non_upper_case_globals)]
#[macro_use]
mod utils;
use num_enum::IntoPrimitive;
use num_enum::TryFromPrimitive;

enum_str! {
enum Color {
	Red = 1,
	Green = 2,
	Yellow = 3,
	Blue = 4,
	Magenta = 5,
	Cyan = 6,
}
}

fn combine_colors(c1:Color, c2:Color) -> Color {
	let i1:isize = c1.into();
	let i2:isize = c2.into();
	let result:isize = i1 | i2;
	let return_color:Color = Color::try_from(result).unwrap();
	return return_color;
}

fn main() {
	let mut c1:Color = Color::Blue;
	println!("c1: {}", c1.name());
	println!("RED: {}", Color::Red.name());
	println!("combineColors(c1, RED): {}", combine_colors(c1, Color::Red).name());
	let c2:Color = Color::Green;
	println!("combineColors(c1, c2): {}", combine_colors(c1, c2).name());
	if c1 == c2 {
		println!("c1 == c2");
	} else {
		println!("c1 != c2");
	}
	c1 = c2;
	if c1 == c2 {
		println!("c1 == c2");
	} else {
		println!("c1 != c2");
	}
	let bad:Color = Color::try_from(7).unwrap();
	println!("bad: {}", bad.name());
}

Output

$ rustc Enums2.rs error[E0423]: expected value, found enum `Color` --> Enums2.rs:38:32 | 38 | let mut bad:Color = intToEnum(Color,7); | ^^^^^ | note: the enum is defined here --> Enums2.rs:3:1 | 3 | / enum Color { 4 | | RED = 1, 5 | | GREEN = 2, 6 | | YELLOW = 3, ... | 9 | | CYAN = 6 10 | | } | |_^ help: you might have meant to use one of the following enum variants | 38 | let mut bad:Color = intToEnum(Color::BLUE,7); | ~~~~~~~~~~~ 38 | let mut bad:Color = intToEnum(Color::CYAN,7); | ~~~~~~~~~~~ 38 | let mut bad:Color = intToEnum(Color::GREEN,7); | ~~~~~~~~~~~~ 38 | let mut bad:Color = intToEnum(Color::MAGENTA,7); | ~~~~~~~~~~~~~~ and 2 other candidates error[E0425]: cannot find function `enumToInt` in this scope --> Enums2.rs:13:17 | 13 | let i1:isize = enumToInt(c1); | ^^^^^^^^^ not found in this scope error[E0425]: cannot find function `enumToInt` in this scope --> Enums2.rs:14:17 | 14 | let i2:isize = enumToInt(c2); | ^^^^^^^^^ not found in this scope error[E0425]: cannot find function `intToEnum` in this scope --> Enums2.rs:16:26 | 16 | let returnColor:Color = intToEnum("Color",result); | ^^^^^^^^^ not found in this scope error[E0277]: `Color` doesn't implement `std::fmt::Display` --> Enums2.rs:22:21 | 22 | println!("c1: {}", c1); | ^^ `Color` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Color` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0277]: `Color` doesn't implement `std::fmt::Display` --> Enums2.rs:23:22 | 23 | println!("RED: {}", Color::RED); | ^^^^^^^^^^ `Color` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Color` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0277]: `Color` doesn't implement `std::fmt::Display` --> Enums2.rs:24:41 | 24 | println!("combineColors(c1, RED): {}", combineColors(c1, Color::RED)); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Color` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Color` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0277]: `Color` doesn't implement `std::fmt::Display` --> Enums2.rs:26:40 | 26 | println!("combineColors(c1, c2): {}", combineColors(c1, c2)); | ^^^^^^^^^^^^^^^^^^^^^ `Color` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Color` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0369]: binary operation `==` cannot be applied to type `Color` --> Enums2.rs:27:8 | 27 | if c1 == c2 { | -- ^^ -- Color | | | Color | note: an implementation of `PartialEq` might be missing for `Color` --> Enums2.rs:3:1 | 3 | enum Color { | ^^^^^^^^^^ must implement `PartialEq` help: consider annotating `Color` with `#[derive(PartialEq)]` | 3 + #[derive(PartialEq)] 4 | enum Color { | error[E0369]: binary operation `==` cannot be applied to type `Color` --> Enums2.rs:33:8 | 33 | if c1 == c2 { | -- ^^ -- Color | | | Color | note: an implementation of `PartialEq` might be missing for `Color` --> Enums2.rs:3:1 | 3 | enum Color { | ^^^^^^^^^^ must implement `PartialEq` help: consider annotating `Color` with `#[derive(PartialEq)]` | 3 + #[derive(PartialEq)] 4 | enum Color { | error[E0425]: cannot find function `intToEnum` in this scope --> Enums2.rs:38:22 | 38 | let mut bad:Color = intToEnum(Color,7); | ^^^^^^^^^ not found in this scope error: aborting due to 11 previous errors Some errors have detailed explanations: E0277, E0369, E0423, E0425. For more information about an error, try `rustc --explain E0277`.

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References

[[Rust Language Reference]]
[[Rust Compiler]]