The with macro

This is a macro that takes an object and lets you call methods on that object without naming it. The first argument is an expression that will be assigned to a variable in let binding. To make that binding mutable, prepend mut to the expression. Calling a function that starts with a . will be converted into a method call using this variable.

The supported forms are:

• .method(args..)
• let pat = .method(args..);
• var = .method(args..);

Anything else will be evaluated unmodified as an expression.

Usage

use with_macro::with;

let vec = with! {
    mut Vec::new() =>
        .push(1)
        .push(42)
        .push(-13)
        let l = .len();
        assert_eq!(l, 3);
};

assert_eq!(vec, [1, 42, -13]);