Purpose

This tilde crate utilizes the disused tilde operator ~ to generate syntatic sugar for Rust program.

Features

1. Postfix macro. The syntax is first_arg.~the_macro!(rest_args), which will be desugared as the_macro!( first_arg, rest_args ). As proposed in simple postfix macros #2442, first_arg will be evaluated excactly once.

Example: Postfix macro

rust macro_rules! inc { ($e:expr) => { $e+1 }}

Suppose i: i32, The library user could write: i.~inc!(), i.clone().~inc!() etc, which is a sugar as inc!( i ) and inc!( i.clone() ).

This feature is in compliance with RFC 2442:

```rust macrorules! logvalue { ( $self:expr, $msg:expr ) => ({ $self.1.push_str( &format!( "{}:{}: {}: {:?}", file!(), line!(), $msg, $self.0 )); $self }) }

fn value( x: T, log: &mut String ) -> (T,&mut String) { log.push_str( &format!( "evaluated {:?}\n", x )); ( x, log ) }

tilde! { #[test] fn rfcpr2442() { let mut log1 = String::new(); let mut log2 = String::new(); ( value( "hello", &mut log1 ).~logvalue!( "value" ).0.len(), &mut log2 ).~logvalue!( "len" ); let log = format!( "{}\n{}", log1, log2 ); asserteq!( log, r#"evaluated "hello" tildederive/src/lib.rs:72: value: "hello" tilde_derive/src/lib.rs:72: len: 5"# ); } } ```

More features will be added in the future.

License

Licensed under MIT.