Finished basic google home implementation with some slight refactors along the way

impl_cast/.gitignore

@@ -0,0 +1 @@
+/target

impl_cast/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "impl_cast"
+version = "0.1.0"
+dependencies = [
+ "paste",
+]
+
+[[package]]
+name = "paste"
+version = "1.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf1c2c742266c2f1041c914ba65355a83ae8747b05f208319784083583494b4b"

impl_cast/Cargo.toml

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+[package]
+name = "impl_cast"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+paste = "1.0.10"

impl_cast/src/lib.rs

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+pub extern crate paste;
+
+#[macro_export]
+macro_rules! impl_cast {
+    ($base:ident, $trait:ident) => {
+        $crate::paste::paste! {
+            pub trait [< As $trait>] {
+                fn cast(&self) -> Option<&dyn $trait>;
+                fn cast_mut(&mut self) -> Option<&mut dyn $trait>;
+            }
+
+            impl<T: $base> [< As $trait>] for T {
+                default fn cast(&self) -> Option<&dyn $trait> {
+                    None
+                }
+                default fn cast_mut(&mut self) -> Option<&mut dyn $trait> {
+                    None
+                }
+            }
+
+            impl<T: $base + $trait> [< As $trait>] for T {
+                fn cast(&self) -> Option<&dyn $trait> {
+                    Some(self)
+                }
+                fn cast_mut(&mut self) -> Option<&mut dyn $trait> {
+                    Some(self)
+                }
+            }
+        }
+    };
+}