#struct #anonymous #named #arguments #lens


Simulating anonymous struct and named arguments in Rust

7 releases

0.1.6 May 18, 2021
0.1.5 Apr 13, 2021
0.1.3 Mar 19, 2021

#994 in Rust patterns

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See RFC as Readme-For-Crate for more.


This project provides simulation of anonymous struct and named arguments in Rust, using proc macros structx!{}, Structx!{}, #[named_args] and args!{}.

Usage of this crate

Add the following in your Cargo.toml file:

structx = "0.1"

structx = true

Add the following in your .rs files:

use structx::*;

If you want to use named arguments, add the following:

use structx::named_args::*;

Definitions and notations of anonymous structs

Anonymous structs are structs without the needs of providing struct names. However, the field names are mandatory. Anonymous structs are of the same type if and only if they are composed of the same set of field names. The order of fields are irrelevant.

Value of anonymous structs

The notation of an anonymous struct's value is structx!{}.

Examples of anonymous struct's values

let foo = structx!{ i: 3, b: true };
let bar = structx!{ x, y };

Type of anonymous structs

The notation of an anonymous struct's type is Structx!{}.

Examples of anonymous struct's types

fn foo( x: i32, y: i32 ) -> Structx!{ x: i32, y: i32 } {
    structx!{ x, y: y+1 }

Traits derived for anonymous structs

Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash.

let a = structx!{ width :  800, height: 600 };
let b = structx!{ height:  600, width : 800 };
let c = structx!{ width : 1024, height: 768 };
assert_eq!( a, b );
assert_ne!( a, c );

Simulation of named arguments

At definition site, add attributes #[named_args] to functions.

fn set_size( width: u32, height: u32 ) { todo!() }

At call site, wrap arguments with args!{}.

set_size( args!{ width: 1024, height: 768 });


Under Apache License 2.0 or MIT License, at your will.


~20K SLoC