Trying to generate doc comments with macros

help
1

Hi!
I have a struct called Builder that I use a macro to define setters on.

///Creates a builder function that sets $name.
macro_rules! builder_fn_set {
	{ $name: ident >< $type: ty } => {
		#[allow(dead_code)]
		pub fn $name(mut self, $name: $type) -> Self {
			self.$name = $name;
			self
		}
	};
	{ $name: ident <> $type: ty } => {
		#[allow(dead_code)]
		#[doc="Sets $name of this builder to Some($name)."]
		pub fn $name(mut self, $name: $type) -> Self {
			self.$name = Some($name);
			self
		}
	};
}
pub struct Builder {
	width : Option<u32>,
	height: Option<u32>,
	cells_x: Option<u32>,
	cells_y: Option<u32>,
	wrap: bool
}

///A builder for a Tiler Class.
impl Builder {
	builder_fn_set!{ width   <> u32  }
	builder_fn_set!{ height  <> u32  }
	builder_fn_set!{ cells_x <> u32  }
	builder_fn_set!{ cells_y <> u32  }
	builder_fn_set!{ wrap    >< bool }
        //...
}

My issue is that the docs come out as "Sets $name of this builder to Some($name)." It doesn't parse the $name argument into the doc comment.

2

A string literal is a string literal; macros don't treat them specially. You can't interpolate directly into a string literal from a declarative macro.

Fortunately, the #[doc] attribute can be repeated, so you can write

		#[doc = "Sets "]
		#[doc = stringify!($name)]
		#[doc = " of this builder to Some("]
		#[doc = stringify!($name)]
		#[doc = ")."]

Playground

3

Nice! This works well, but I notice it says "Some( u32 )" instead of "Some(u32)". Is it possible to remove the spacing?

4

You can try and see if concat!() works in attribute context too.

5

Concat! works well. You still have to use the stringify! macro for idents and tys. Thanks!

6

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