episode 14

Author: Byron

Cargo.lock

@@ -1,2 +1,2 @@
 [workspace]
-members = ["./ownership-and-borrowing", "options-and-results", "errors", "iterators", "strings", "boxing"]
+members = ["./ownership-and-borrowing", "options-and-results", "errors", "iterators", "strings", "boxing", "conversions"]

Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "conversions"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

conversions/Cargo.toml

@@ -0,0 +1,65 @@
+#![allow(unused)]
+
+struct A;
+struct B;
+struct C;
+
+impl From<B> for A {
+    fn from(_: B) -> Self {
+        A
+    }
+}
+impl From<C> for A {
+    fn from(_: C) -> Self {
+        A
+    }
+}
+
+fn foo(a: impl Into<A>) {
+    let a = a.into();
+}
+fn foo_b(a: B) {
+    foo_inner(a.into())
+}
+fn foo_c(a: C) {
+    foo_inner(a.into())
+}
+fn foo_inner(a: A) {
+    // millions of lines
+}
+
+enum Z {
+    A,
+    ParsedC,
+}
+
+impl From<A> for Z {
+    fn from(_: A) -> Self {
+        Z::A
+    }
+}
+
+impl TryFrom<C> for Z {
+    type Error = ();
+
+    fn try_from(value: C) -> Result<Self, Self::Error> {
+        Err(())
+    }
+}
+
+fn main() {
+    let a: A = B.into();
+    let a = Into::<A>::into(B);
+    let a = A::from(B);
+    let a = A::from(C);
+    let a: A = C.into();
+
+    let x: u32 = "8".parse().unwrap();
+    let z: Z = A.into();
+    let z: Z = A.try_into().unwrap();
+    let z: Z = C.try_into().unwrap();
+
+    foo(B);
+    foo(C);
+    foo(A);
+}