features: init, preposition

exercises/features/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "features"
+version = "0.0.1"
+edition = "2018"
+
+[lib]
+name = "features1"
+path = "src/features1.rs"
+
+[features]
+english = []
+russian = []
+korean = []

exercises/features/README.md

@@ -0,0 +1,5 @@
+For this exercise check out the sections:
+- [Features](https://doc.rust-lang.org/cargo/reference/features.html)
+- [Conditional Compilation](https://doc.rust-lang.org/reference/conditional-compilation.html)
+
+of the Rust Book.

exercises/features/src/features1.rs

@@ -0,0 +1,48 @@
+// features1.rs
+// Conditional compilation example:
+// `cargo +stable test --features "english" --release`
+// `cargo +stable test --features "korean" --release`
+// `cargo +stable test --features "russian" --release`
+// https://doc.rust-lang.org/cargo/reference/features.html
+// https://doc.rust-lang.org/reference/conditional-compilation.html
+// Also, try `cargo expand` https://github.com/dtolnay/cargo-expand
+// `cargo expand --features "russian"`
+// Execute `rustlings hint features1` for hints!
+
+// I AM NOT DONE
+
+#[cfg(feature = "korean")]
+pub fn hello() -> String {
+    String::from("안녕하세요!")
+}
+
+#[cfg(feature = "russian")]
+pub fn hello() -> String {
+    String::from("Привет мир!")
+}
+
+#[cfg(feature = "english")]
+pub fn hello() -> String {
+    String::from("Hello World!")
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::hello;
+
+    #[test]
+    fn say_hello() {
+        #[cfg(feature = "korean")]
+        let r = "안녕하세요!".to_string();
+
+        #[cfg(feature = "english")]
+        let r = "Hello World!".to_string();
+
+        #[cfg(feature = "russian")]
+        let r = "Привет мир!".to_string();
+
+        let a = hello();
+
+        assert_eq!(r, a);
+    }
+}

info.toml

@@ -419,6 +419,15 @@ path = "exercises/quiz4.rs"
 mode = "test"
 hint = "No hints this time ;)"
 
+# FEATURES
+
+[[exercies]]
+name = "features1"
+path = "exercises/features/src/features1.rs"
+mode = "feature"
+hint = """TODO: Add some nice hint!"""
+features = ["english", "korean", "russian"]
+
 # MOVE SEMANTICS
 
 [[exercises]]