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+//! Example Lazy Resources
+//!
+//! > This example demonstrates how to use `LazyRes` for lazy resource initialization.
+//!
+//! Run:
+//! ```bash
+//! cargo run --manifest-path examples/example-lazy-resources/Cargo.toml --quiet none
+//!
+//! cargo run --manifest-path examples/example-lazy-resources/Cargo.toml --quiet show
+//! ```
+//!
+//! Output:
+//! ```plaintext
+//! None
+//!
+//! Initialized
+//! foo: bar
+//! rust: lang
+//! baz: qux
+//! hello: world
+//! key: value
+//! ```
+
+use std::collections::BTreeMap;
+
+use mingling::{LazyInit, LazyRes, prelude::*};
+
+type Key = String;
+type Value = String;
+
+// Define a resource that requires time-consuming initialization
+#[derive(Default, Clone)]
+pub struct ResLargeData {
+ pub data: BTreeMap<Key, Value>,
+}
+
+fn init_res_large_data() -> ResLargeData {
+ // Perform time-consuming initialization here
+ let mut data = BTreeMap::new();
+ data.insert("foo".to_string(), "bar".to_string());
+ data.insert("baz".to_string(), "qux".to_string());
+ data.insert("hello".to_string(), "world".to_string());
+ data.insert("rust".to_string(), "lang".to_string());
+ data.insert("key".to_string(), "value".to_string());
+
+ // Print to indicate initialization is complete
+ println!("Initialized");
+ ResLargeData { data }
+}
+
+dispatcher!("show", CMDShow => EntryShow);
+dispatcher!("none", CMDNone => EntryNone);
+
+pack!(ResultShow = BTreeMap<Key, Value>);
+
+fn main() {
+ let mut program = ThisProgram::new();
+
+ // --------- IMPORTANT ---------
+ // _ Use lazy_init to create LazyRes<ResLargeData>
+ // /
+ // vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
+ program.with_resource(ResLargeData::lazy_init(init_res_large_data));
+ // --------- IMPORTANT ---------
+
+ program.with_dispatchers((CMDShow, CMDNone));
+ program.exec_and_exit();
+}
+
+// Inject LazyRes instead of a normal resource
+// __________________________ Must use &mut because `get_ref` and `get_mut`
+// / both require mutable borrow
+// | _____________________ Use LazyRes<ResLargeData>
+// | / instead of ResLargeData
+#[renderer] // vvvv vvvvvvvvvvvvvvvvvvvvv
+fn render_entry_show(_args: EntryShow, res: &mut LazyRes<ResLargeData>) {
+ // _______ Initialization happens here
+ // /
+ // vvvvvvv
+ let res = res.get_ref();
+ for (key, value) in &res.data {
+ r_println!("{}: {}", key, value);
+ }
+}
+
+// When not using LazyRes<ResLargeData>, it will not be initialized
+#[renderer]
+fn render_entry_none(_args: EntryNone) {
+ r_println!("None");
+}
+
+gen_program!();