initial commit

exercises/06_ticket_management/09_impl_trait_2/Cargo.toml

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+[package]
+name = "impl_trait_2"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+ticket_fields = { path = "../../../helpers/ticket_fields" }

exercises/06_ticket_management/09_impl_trait_2/src/lib.rs

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+// TODO: Rework the signature of `TicketStore::add_ticket` to use a generic type parameter rather
+//  than `impl Trait` syntax.
+
+use ticket_fields::{TicketDescription, TicketTitle};
+
+#[derive(Clone)]
+pub struct TicketStore {
+    tickets: Vec<Ticket>,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Ticket {
+    pub title: TicketTitle,
+    pub description: TicketDescription,
+    pub status: Status,
+}
+
+#[derive(Clone, Debug, Copy, PartialEq)]
+pub enum Status {
+    ToDo,
+    InProgress,
+    Done,
+}
+
+impl TicketStore {
+    pub fn new() -> Self {
+        Self {
+            tickets: Vec::new(),
+        }
+    }
+
+    // Using `Into<Ticket>` as the type parameter for `ticket` allows the method to accept any type
+    // that can be infallibly converted into a `Ticket`.
+    // This can make it nicer to use the method, as it removes the syntax noise of `.into()`
+    // from the calling site. It can worsen the quality of the compiler error messages, though.
+    pub fn add_ticket(&mut self, ticket: impl Into<Ticket>) {
+        self.tickets.push(ticket.into());
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ticket_fields::test_helpers::{ticket_description, ticket_title};
+
+    struct TicketDraft {
+        pub title: TicketTitle,
+        pub description: TicketDescription,
+    }
+
+    impl From<TicketDraft> for Ticket {
+        fn from(draft: TicketDraft) -> Self {
+            Self {
+                title: draft.title,
+                description: draft.description,
+                status: Status::ToDo,
+            }
+        }
+    }
+
+    #[test]
+    fn generic_add() {
+        let mut store = TicketStore::new();
+        // This won't compile if `add_ticket` uses `impl Trait` syntax in argument position.
+        store.add_ticket::<TicketDraft>(TicketDraft {
+            title: ticket_title(),
+            description: ticket_description(),
+        });
+    }
+}