libcruft-util/except.hpp

/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2018 Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include <iosfwd>

namespace cruft {
    /// A base exception class for all cruft libraries.
    ///
    /// There is deliberately no `what` method as it's not always acceptable
    /// to store a string that we can return a pointer to. Instead we rely on
    /// the `describe` method to output to a std::ostream. The user can wrangle
    /// that into a std::string if they need one.
    class error {
    public:
        virtual ~error () = default;
        virtual std::ostream& describe (std::ostream&) const noexcept = 0;
    };


    /// Use `error::describe` to render the supplied error object to a
    /// std::ostream.
    std::ostream&
    operator<< (std::ostream &os, error const&);
}