DispatchQueue.future

DispatchQueue+future.swift

import Foundation
import Combine

extension DispatchQueue {
    /// Run a closure on a dispatch queue asyncronously.
    /// - Returns a future.
    func future<Output>(
        perform: @escaping () -> Output
    ) -> Future<Output, Never> {
        Future<Output, Never> { promise in
            self.async {
                let output = perform()
                promise(Result.success(output))
            }
        }
    }
    
    /// Run a throwing closure on a dispatch queue asyncronously.
    /// - Returns a future.
    func future<Output>(
        perform: @escaping () throws -> Output
    ) -> Future<Output, Error> {
        Future<Output, Error> { promise in
            self.async {
                do {
                    let output = try perform()
                    promise(Result.success(output))
                } catch {
                    promise(Result.failure(error))
                }
            }
        }
    }
}