Document Callable, Trap, HostRef, and ValType (#693)

crates/api/src/trap.rs

@@ -1,5 +1,7 @@
 use thiserror::Error;
 
+/// A struct representing an aborted instruction execution, with a message
+/// indicating the cause.
 #[derive(Error, Debug)]
 #[error("Wasm trap: {message}")]
 pub struct Trap {
@@ -7,14 +9,25 @@ pub struct Trap {
 }
 
 impl Trap {
-    pub fn new(message: String) -> Trap {
-        Trap { message }
+    /// Creates a new `Trap` with `message`.
+    /// # Example
+    /// ```
+    /// let trap = wasmtime::Trap::new("unexpected error");
+    /// assert_eq!("unexpected error", trap.message());
+    /// ```
+    pub fn new<I: Into<String>>(message: I) -> Trap {
+        Self {
+            message: message.into(),
+        }
     }
 
+    /// Create a `Trap` without defining a message for the trap. Mostly useful
+    /// for prototypes and tests.
     pub fn fake() -> Trap {
-        Trap::new("TODO trap".to_string())
+        Self::new("TODO trap")
     }
 
+    /// Returns a reference the `message` stored in `Trap`.
     pub fn message(&self) -> &str {
         &self.message
     }