- Originally forked from paste 1.0.15
- Will be maintained (depenencies/crates updated & CVEs addressed in a timely manner, etc.)
- Will pick up where the author left off in terms of semantic versioning (author's last release version was 1.0.15, our first version is 1.1.0)
- Several security scanners have been added to the repo to ensure any issues are found quickly
- Minor code/comment additions to streamline compatibility
- Rust edition updated from 2018 to 2021 without build/unit test errors
- MSRV (minimum supported Rust version) updated from 1.31 to 1.85 without build/unit test errors
Disclaimer: this project is stable and can be used in production environments, but SLA-based support won't be offered until we're at v1.2 and/or sponsored. 
The nightly-only 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 macro_paste together identifiers in a macro, including using pasted identifiers to define new items.
[dependencies]
macro_paste = "1.0"This approach works with any Rust compiler 1.31+.
Within the macro_paste! macro, identifiers inside [<...>] are pasted together to
form a single identifier.
use macro_paste::macro_paste;
macro_paste! {
// Defines a const called `QRST`.
const [<Q R S T>]: &str = "success!";
}
fn main() {
assert_eq!(
macro_paste! { [<Q R S T>].len() },
8,
);
}The next example shows a macro that generates accessor methods for some struct fields. It demonstrates how you might find it useful to bundle a macro_paste invocation inside of a macro_rules macro.
use macro_paste::macro_paste;
macro_rules! make_a_struct_and_getters {
($name:ident { $($field:ident),* }) => {
// Define a struct. This expands to:
//
// pub struct S {
// a: String,
// b: String,
// c: String,
// }
pub struct $name {
$(
$field: String,
)*
}
// Build an impl block with getters. This expands to:
//
// impl S {
// pub fn get_a(&self) -> &str { &self.a }
// pub fn get_b(&self) -> &str { &self.b }
// pub fn get_c(&self) -> &str { &self.c }
// }
macro_paste! {
impl $name {
$(
pub fn [<get_ $field>](&self) -> &str {
&self.$field
}
)*
}
}
}
}
make_a_struct_and_getters!(S { a, b, c });
fn call_some_getters(s: &S) -> bool {
s.get_a() == s.get_b() && s.get_c().is_empty()
}Use $var:lower or $var:upper in the segment list to convert an interpolated
segment to lower- or uppercase as part of the macro_paste. For example, [<ld_ $reg:lower _expr>] would macro_paste to ld_bc_expr if invoked with $reg=Bc.
Use $var:snake to convert CamelCase input to snake_case.
Use $var:camel to convert snake_case to CamelCase.
These compose, so for example $var:snake:upper would give you SCREAMING_CASE.
The precise Unicode conversions are as defined by str::to_lowercase and
str::to_uppercase.
Within the macro_paste! macro, arguments to a #[doc ...] attribute are implicitly
concatenated together to form a coherent documentation string.
use macro_paste::macro_paste;
macro_rules! method_new {
($ret:ident) => {
macro_paste! {
#[doc = "Create a new `" $ret "` object."]
pub fn new() -> $ret { todo!() }
}
};
}
pub struct macro_paste {}
method_new!(macro_paste); // expands to #[doc = "Create a new `macro_paste` object"]Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
