Merge pull request #201 from phil-opp/lazy_static

Use upstream lazy_static and upgrade `once` to latest version

Cargo.toml

@@ -6,7 +6,7 @@ version = "0.1.0"
 [dependencies]
 bit_field = "0.1.0"
 bitflags = "0.7.0"
-once = "0.2.1"
+once = "0.3.2"
 rlibc = "0.1.4"
 spin = "0.3.4"
 
@@ -20,6 +20,10 @@ git = "https://github.com/phil-opp/multiboot2-elf64"
 default-features = false
 version = "0.7.1"
 
+[dependencies.lazy_static]
+version = "0.2.1"
+features = ["spin_no_std"]
+
 [lib]
 crate-type = ["staticlib"]
 

blog/post/2016-05-28-catching-exceptions.md

@@ -435,6 +435,24 @@ The reason is that the Rust compiler is not able to evaluate the value of the `s
 #### Lazy Statics to the Rescue
 Fortunately the `lazy_static` macro exists. Instead of evaluating a `static` at compile time, the macro performs the initialization when the `static` is referenced the first time. Thus, we can do almost everything in the initialization block and are even able to read runtime values.
 
+Let's add the `lazy_static` crate to our project:
+
+```rust
+// in src/lib.rs
+
+#[macro_use]
+extern crate lazy_static;
+```
+
+```toml
+# in Cargo.toml
+
+[dependencies.lazy_static]
+version = "0.2.1"
+features = ["spin_no_std"]
+```
+We need the `spin_no_std` feature, since we don't link the standard library.
+
 With `lazy_static`, we can define our IDT without problems:
 
 ```rust

src/lib.rs

@@ -24,6 +24,8 @@ extern crate x86;
 #[macro_use]
 extern crate once;
 extern crate bit_field;
+#[macro_use]
+extern crate lazy_static;
 
 extern crate hole_list_allocator;
 extern crate alloc;