[structx 0.1.0] Anonymous struct and named arguments simulation in Rust

Project: structx

Overview

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:

[dependencies]
structx = "0.1"

[package.metadata.inwelling]
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 struct s 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

Debug, 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.

#[named_args]
fn set_size( width: u32, height: u32 ) { todo!() }

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

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

# Caveat

## Reverse dependency

Collecting types and values of anonymous structs from downstream crates makes crate structx depending on its users. Unfortunately this kind of reverse-dependency is not known to cargo. As a result, the modifications of .rs files which change types and values of anonymous structs will not cause recompilation of crate structx, which it should.

To address this issue, simply do cargo clean , or more precisely, cargo clean --package structx before running cargo build .

(This has been fixed in structx 0.1.2)

License

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

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