Macro do_with_in

do_with_in!() { /* proc-macro */ }

This is the proc_macro most users of this crate will use.

There is front matter, which can define the sigil and escaping style. Escaping doesn’t actually do anything yet though. Then do, then after that is where the metaprogramming can happen.

In the metaprogramming section, variables are identifiers with a sigil prepended. You can create and assign to them with let and var handlers. Numbers with a sigil prepended are special variables that can be set inside a handler; you cannot assign to them with let or var. Brackets with a sigil prepended start a handler invocation; the handler invoked will be the first token inside the brackets, which must be an identifier.

For example, in the following code the sigil is $, $correction_factor is a normal variable, $1, $2, and $3 are special variables set inside the blah handler, and $(let ...), $(mk ...) and $(blah ...) are all handlers.

do_with_in!{
   sigil: $
   do
   $(let correction_factor = {(-1)})
   $(mk blah
       $1 = $2 + $3 + $correction_factor;)
   $(blah {let mut d} 3 4)
   d += 1;
   let correction_factor = $correction_factor;
 };
 assert_eq!(d, 8 + correction_factor);