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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!();
|
