subxt_signer/
utils.rs

1// Copyright 2019-2025 Parity Technologies (UK) Ltd.
2// This file is dual-licensed as Apache-2.0 or GPL-3.0.
3// see LICENSE for license details.
4
5#![allow(unused_macros)]
6
7/// Use like:
8///
9/// ```rust,ignore
10/// once_static_cloned!{
11///     /// Some documentation.
12///     fn foo() -> Vec<u8> {
13///         vec![1,2,3,4]
14///     }
15/// }
16/// ```
17///
18/// Clones the item out of static storage. Useful if it
19/// takes a while to create the item but cloning it is fairly cheap.
20macro_rules! once_static_cloned {
21    ($($(#[$attr:meta])* $vis:vis fn $name:ident() -> $ty:ty { $expr:expr } )+) => {
22        $(
23            $(#[$attr])*
24            #[allow(missing_docs)]
25            $vis fn $name() -> $ty {
26                cfg_if::cfg_if! {
27                    if #[cfg(feature = "std")] {
28                        static VAR: std::sync::OnceLock<$ty> = std::sync::OnceLock::new();
29                        VAR.get_or_init(|| { $expr }).clone()
30                    } else {
31                        { $expr }
32                    }
33                }
34            }
35        )+
36    };
37}
subxt_signer/utils.rs

subxt_signer/
utils.rs
