feat(core): facilitate op-disabling middleware (#11858)

* feat(core): facilitate op-disabling middleware

By providing `void_op_sync()` and `void_op_async() as well as `core/examples/disable_ops.rs`

1 files changed, 27 insertions, 0 deletions

diff --git a/core/examples/disable_ops.rs b/core/examples/disable_ops.rs
new file mode 100644
index 000000000..2d28908bf
--- /dev/null
+++ b/core/examples/disable_ops.rs
@@ -0,0 +1,27 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+//!  This example shows you how to define ops in Rust and then call them from
+//!  JavaScript.
+
+use deno_core::Extension;
+use deno_core::JsRuntime;
+use deno_core::RuntimeOptions;
+
+fn main() {
+  let my_ext = Extension::builder()
+    .middleware(|name, opfn| match name {
+      "op_print" => deno_core::void_op_sync(),
+      _ => opfn,
+    })
+    .build();
+
+  // Initialize a runtime instance
+  let mut runtime = JsRuntime::new(RuntimeOptions {
+    extensions: vec![my_ext],
+    ..Default::default()
+  });
+
+  // Deno.core.print() will now be a NOP
+  runtime
+    .execute_script("<usage>", r#"Deno.core.print("I'm broken")"#)
+    .unwrap();
+}