added modules example

Author: BartMassey

README.md

@@ -15,3 +15,4 @@ in a controlled repository now.
 * `rc`: examples with `RefCell` and `Rc`
 * `readline`: example of readline with error handling
 * `error`: example of creating a custom error
+* `modules`: example of Rust modules

modules/Cargo.toml

@@ -0,0 +1,5 @@
+[package]
+name = "modules"
+version = "0.1.0"
+authors = ["Bart Massey <[email protected]>"]
+edition = "2018"

modules/src/fancymod.rs

@@ -0,0 +1,3 @@
+pub fn fancy_hello() {
+    println!("HELOOO world!!?!");
+}

modules/src/main.rs

@@ -0,0 +1,27 @@
+mod fancymod;
+mod reallyfancymod;
+
+use reallyfancymod::subfn;
+
+mod mymod {
+    pub fn hello() {
+        println!("hello world");
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    const N: u64 = 5;
+
+    #[test]
+    fn my_test() {
+        assert!(N % 2 == 1);
+    }
+}
+
+fn main() {
+    use mymod::*;
+    hello();
+    fancymod::fancy_hello();
+    subfn::really_fancy_hello("me");
+}

modules/src/reallyfancymod/mod.rs

@@ -0,0 +1 @@
+pub mod subfn;

modules/src/reallyfancymod/subfn.rs

@@ -0,0 +1,3 @@
+pub fn really_fancy_hello(who: &str) {
+    println!("helloo? {}?", who);
+}