variant-rs

variant-rs is a Rust crate that provides idiomatic handling of COM VARIANT types. Rust supports discriminated union types out of the box, so although VARIANTs are usually a pain to work with, Rust makes it easy to encode and decode them.

The crate is designed to work with the VARIANT type from the winapi crate.

Basic usage

use variant_rs::*;

fn main() {
    let v1 = Variant::I32(123); // manual instanciation
    let v2 = 123i32.to_variant(); // ToVariant trait
    let v3 = 123.into(); // From / Into traits
    assert_eq!(v1, v2);
    assert_eq!(v1, v3);
  
    let bstr: Variant = "Hello, world!".into();
    let ptr: VARIANT = bstr.clone().try_into().unwrap(); // convert to COM VARIANT
    let back: Variant = ptr.try_into().unwrap(); // convert back
    assert_eq!(bstr, back);
}

Supported VARIANT types and corresponding types

Wrapper types

ComBool

i16-backed enum.

ComCurrency

Maps COM's i64 currency data CY to Decimal.

ComDecimal

Maps COM's 96-bit decimals DECIMAL to Decimal.

ComData

Maps COM's DATE (f64 milliseconds from 1899-12-30) to NaiveDateTime.

PtrWrapper

Safe wrapper around COM interface pointers.

Installation

Add this to your Cargo.toml:

[dependencies]
variant-rs = "0.4.0"

License

This project is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT) at your option.