get-size-derive2 0.11.0

Derives the GetSize trait.
Documentation

get-size-derive2

Crates.io docs.rs MIT licensed

Derives the GetSize trait of get-size2 for structs and enums.

Usage

This crate is re-exported by get-size2, so depend on that with the derive feature instead of adding it directly:

[dependencies]
get-size2 = { version = "^0.10", features = ["derive"] }

use get_size2::GetSize;

#[derive(GetSize)]
struct Data {
    name: String,
    id: u64,
}

assert_eq!(Data { name: "Hello".into(), id: 1 }.get_heap_size(), 5);

The generated implementation sums up the heap size of every field, so every field type has to implement GetSize as well. Shared ownership is deduplicated, since the generated implementation threads a tracker through all fields. Unions are not supported.

Attributes

For fields whose type does not implement GetSize, the #[get_size(...)] attribute offers three ways out, plus a struct or enum level escape hatch for generics:

Attribute Position Effect
#[get_size(ignore)] Field Skips the field, contributing 0
#[get_size(size = 1024)] Field Accounts the field with a fixed number of bytes
#[get_size(size_fn = my_helper)] Field Calls my_helper(&field) to determine the heap size
#[get_size(ignore(A, B))] Struct or enum Drops the GetSize bound on the listed generic types

Documentation

See docs.rs for the full attribute reference with examples, and docs.rs/get-size2 for the trait itself.

License

This library is licensed under the MIT license.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this library by you shall be licensed as MIT, without any additional terms or conditions.