Mercurial > lbo > hg > memoize
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author | Lewin Bormann <lbo@spheniscida.de> |
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date | Thu, 15 Oct 2020 13:34:30 +0200 |
parents | 5b4d00ea008d |
children | 8d44466dbb15 |
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# memoize A `#[memoize]` attribute for somewhat simple Rust functions. That's it. Read the documentation (`cargo doc --open`) for the sparse details, or take a look at the `examples/`, if you want to know more: ```rust use memoize::memoize; #[memoize] fn hello(arg: String) -> bool { arg.len()%2 == 0 } // `hello` is only called once here. assert!(! hello("World".to_string())); assert!(! hello("World".to_string())); // Sometimes one might need the original function. assert!(! memoized_original_hello("World".to_string())); ``` This is, aside from the `assert`s, expanded into: ``` // This is obviously further expanded before compiling. lazy_static! { static ref MEMOIZED_MAPPING_HELLO : Mutex<HashMap<String, bool>>; } fn memoized_original_hello(arg: String) -> bool { arg.len()%2 == 0 } fn hello(arg: String) -> bool { let mut hm = &mut MEMOIZED_MAPPING_HELLO.lock().unwrap(); if let Some(r) = hm.get(&arg) { return r.clone(); } let r = memoized_original_hello(arg.clone()); hm.insert(arg, r.clone()); r } ``` Intentionally not yet on crates.rs.