subsoil 0.2.0

Soil primitives foundation crate
Documentation 
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// This file is part of Soil.

// Copyright (C) Soil contributors.
// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0 OR GPL-3.0-or-later WITH Classpath-exception-2.0

//! Stores the externalities in an `environmental` value to make it scope limited available.

use super::Externalities;

environmental::environmental!(ext: trait Externalities);

/// Set the given externalities while executing the given closure. To get access to the
/// externalities while executing the given closure [`with_externalities`] grants access to them.
/// The externalities are only set for the same thread this function was called from.
pub fn set_and_run_with_externalities<F, R>(ext: &mut dyn Externalities, f: F) -> R
where
	F: FnOnce() -> R,
{
	ext::using(ext, f)
}

/// Execute the given closure with the currently set externalities.
///
/// Returns `None` if no externalities are set or `Some(_)` with the result of the closure.
pub fn with_externalities<F: FnOnce(&mut dyn Externalities) -> R, R>(f: F) -> Option<R> {
	ext::with(f)
}