Macros for all your token pasting needs
concat_idents! macro in the Rust standard library is
notoriously underpowered in that its concatenated identifiers can only refer to
existing items, they can never be used to define something new.
This crate provides a flexible way to paste together identifiers in a macro, including using pasted identifiers to define new items.
 = "0.1"
This approach works with any stable or nightly Rust compiler 1.30+.
There are two entry points,
paste::expr! for macros in expression position and
paste::item! for macros in item position.
Within either one, identifiers inside
>] are pasted together to form a
// Macro in item position: at module scope or inside of an impl block. item!
More elaborate examples
This program demonstrates how you may want to bundle a paste invocation inside
of a more convenient user-facing macro of your own. Here the
macro expands to a vector containing
const ROUTE_A: &str = "/a"; const ROUTE_B: &str = "/b";
The next example shows a macro that generates accessor methods for some struct fields.
make_a_struct_and_getters!; } }
$var:upper in the segment list to convert an interpolated
segment to lower- or uppercase as part of the paste. For example,
[<ld_ $reg:lower _expr>] would paste to
ld_bc_expr if invoked with $reg=
$var:snake to convert CamelCase input to snake_case.
$var:camel to convert snake_case to CamelCase.
These compose, so for example
$var:snake:upper would give you SCREAMING_CASE.