A Box wrapper without generic type that allows dynamic dispatch / downcast but without using fat pointer.
Provides a dynamic box type BoxAny, which contains a Box<T> value.
BoxAny is similar to Box<dyn Any> but it doesn't use
fat pointer to dynamic dispatch.
In this benchmark bench we create a Vec container composed by 4 Vec with different types (u8, u16, u32, u64) and then we insert 1M integer for each Vec type (Vec<u8>, Vec<u16>, Vec<u32>, Vec<u64>). To do this we use and compare two different approach:
- dyn box (dyn Trait standard approach): we create a Vec container with type:
Vec<Box<dyn Array>>and we use downcast + push method to insert 1M integer for each Vec type. - box_any: we create a Vec container with type
Vec<BoxAny>and we useBoxAnydowncast + push method to insert 1M integer for each Vec type.
As we can see from the result, using BoxAny approach to downcast and fill each Vec is faster then using dyn Trait approach.
cargo bench
Finished bench [optimized] target(s) in 0.03s
Running unittests src/lib.rs (target/release/deps/box_any-d326196ff75eb72f)
running 1 test
test tests::test ... ignored
test result: ok. 0 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 0.00s
Running benches/bench.rs (target/release/deps/bench-06d6896e0a110c0e)
dyn box checked time: [14.393 ms 14.410 ms 14.431 ms]
change: [-3.8738% -2.8496% -2.0529%] (p = 0.00 < 0.05)
Performance has improved.
Found 10 outliers among 100 measurements (10.00%)
6 (6.00%) high mild
4 (4.00%) high severe
box_any checked time: [5.5236 ms 5.6059 ms 5.7449 ms]
change: [-8.4525% -5.6854% -2.4171%] (p = 0.00 < 0.05)
Performance has improved.
Found 13 outliers among 100 measurements (13.00%)
8 (8.00%) high mild
5 (5.00%) high severe
box_any checked #2 time: [4.2085 ms 4.2173 ms 4.2287 ms]
change: [-6.8000% -6.2270% -5.7308%] (p = 0.00 < 0.05)
Performance has improved.
Found 15 outliers among 100 measurements (15.00%)
5 (5.00%) high mild
10 (10.00%) high severe
use std::any:: TypeId;
use box_any::BoxAny;
let box_u32 = Box::new(032);
let box_string = Box::new(String::from("Hello World"));
let box_any_u32: BoxAny = box_u32.clone().into();
let box_any_string: BoxAny = box_string.clone().into();
let box_any_vec: Vec<BoxAny> = vec![box_any_u32, box_any_string];
assert!(box_any_vec[1].is::<String>());
let string_2: &String = box_any_vec[1].downcast_ref::<String>().unwrap();
assert_eq!(string_2, box_string.as_ref());
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