cleanup(core/example/hello_world): use Deno.core.print instead of new op (#10645)

core/examples/hello_world.rs

@@ -4,54 +4,16 @@
 
 use deno_core::op_sync;
 use deno_core::JsRuntime;
-use deno_core::ZeroCopyBuf;
-use std::io::Write;
 
 fn main() {
   // Initialize a runtime instance
   let mut runtime = JsRuntime::new(Default::default());
 
-  // The first thing we do is define two ops.  They will be used to show how to
+  // Register an op for summing a number array.
-  // pass data to Rust and back to JavaScript.
-  //
-  // The first one is used to print data to stdout, because by default the
-  // JavaScript console functions are just stubs (they don't do anything).
-  //
-  // The second one just transforms some input and returns it to JavaScript.
-
-  // Register the op for outputting a string to stdout.
-  // It can be invoked with Deno.core.opcall and the id this method returns
-  // or Deno.core.opSync   and the name provided.
-  runtime.register_op(
-    "op_print",
-    // The op_fn callback takes a state object OpState,
-    // a structured arg of type `T` and an optional ZeroCopyBuf,
-    // a mutable reference to a JavaScript ArrayBuffer
-    op_sync(
-      |_state, msg: Option<String>, zero_copy: Option<ZeroCopyBuf>| {
-        let mut out = std::io::stdout();
-
-        // Write msg to stdout
-        if let Some(msg) = msg {
-          out.write_all(msg.as_bytes()).unwrap();
-        }
-
-        // Write the contents of every buffer to stdout
-        if let Some(buf) = zero_copy {
-          out.write_all(&buf).unwrap();
-        }
-
-        Ok(()) // No meaningful result
-      },
-    ),
-  );
-
-  // Register the JSON op for summing a number array.
   runtime.register_op(
     "op_sum",
-    // The op_sync function automatically deserializes
+    // The op-layer automatically deserializes inputs
-    // the first ZeroCopyBuf and serializes the return value
+    // and serializes the returned Result & value
-    // to reduce boilerplate
     op_sync(|_state, nums: Vec<f64>, _: ()| {
       // Sum inputs
       let sum = nums.iter().fold(0.0, |a, v| a + v);
@@ -61,28 +23,18 @@ fn main() {
   );
   runtime.sync_ops_cache();
 
-  // Now we see how to invoke the ops we just defined. The runtime automatically
+  // Now we see how to invoke the op we just defined. The runtime automatically
   // contains a Deno.core object with several functions for interacting with it.
   // You can find its definition in core.js.
-  runtime
-    .execute(
-      "<init>",
-      r#"
-// Define a print function that uses
-// our op_print op to display the stringified argument.
-const _newline = new Uint8Array([10]);
-function print(value) {
-  Deno.core.opSync('op_print', value.toString(), _newline);
-}
-"#,
-    )
-    .unwrap();
-
-  // Now we can finally use this in an example.
   runtime
     .execute(
       "<usage>",
       r#"
+// Print helper function, calling Deno.core.print()
+function print(value) {
+  Deno.core.print(value.toString()+"\n");
+}
+
 const arr = [1, 2, 3];
 print("The sum of");
 print(arr);