Merge pull request #57 from QuietMisdreavus/macros

add macros examples

macros/macros1.rs

@@ -0,0 +1,62 @@
+// Make me compile! Scroll down for hints :)
+
+macro_rules! my_macro {
+    () => {
+        println!("Check out my macro!");
+    };
+}
+
+fn main() {
+    my_macro();
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// When you call a macro, you need to add something special compared to a regular function call. If
+// you're stuck, take a look at what's inside `my_macro`.

macros/macros2.rs

@@ -0,0 +1,72 @@
+// Make me compile! Scroll down for hints :)
+
+fn main() {
+    my_macro!();
+}
+
+macro_rules! my_macro {
+    () => {
+        println!("Check out my macro!");
+    };
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// Macros don't quite play by the same rules as the rest of Rust, in terms of what's available
+// where.
+
+
+
+
+
+
+
+
+// Unlike other things in Rust, the order of "where you define a macro" versus "where you use it"
+// actually matters.

macros/macros3.rs

@@ -0,0 +1,74 @@
+// Make me compile, without taking the macro out of the module! Scroll down for hints :)
+
+mod macros {
+    macro_rules! my_macro {
+        () => {
+            println!("Check out my macro!");
+        };
+    }
+}
+
+fn main() {
+    my_macro!();
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// In order to use a macro outside of its module, you need to do something special to the module to
+// lift the macro out into its parent.
+
+
+
+
+
+
+
+
+// The same trick also works on "extern crate" statements for crates that have exported macros, if
+// you've seen any of those around.

macros/macros4.rs

@@ -0,0 +1,76 @@
+// Make me compile! Scroll down for hints :)
+
+macro_rules! my_macro {
+    () => {
+        println!("Check out my macro!");
+    }
+    ($val:expr) => {
+        println!("Look at this other macro: {}", $val);
+    }
+}
+
+fn main() {
+    my_macro!();
+    my_macro!(7777);
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// You only need to add a single character to make this compile.
+
+
+
+
+
+
+
+
+
+// The way macros are written, it wants to see something between each "macro arm", so it can
+// separate them.