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/*
* Copyright (C) 2021 Niels De Graef <nielsdegraef@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* Contacts.Operation is a simple interface to describe actions that can be
* executed and possibly undone later on (for example, using a button on an
* in-app notification).
*
* Since some operations might not be able undoable later onwards, there is a
* property `reversable` that you should check first before calling undo().
*
* Note that you probably shouldn't be calling the execute() method directly,
* but use the API provided by {@link OperationQueue} instead.
*/
public abstract class Contacts.Operation : Object {
/** The UUID of the operation */
public string uuid { get; private set; default = Uuid.string_random (); }
/**
* Whether undo() can be called on this object
*/
public abstract bool reversable { get; }
/**
* A user-facing string that tells us what the operation does
*/
public abstract string description { owned get; }
/**
* This the actual implementation of the operation that a subclass needs to
* implement.
*/
public abstract async void execute () throws GLib.Error;
/**
* The is the public API undo. If you want, you can override it still, e.g.
* to provide better warnings.
*/
public virtual async void undo () throws GLib.Error {
// FIXME: should throw an error instead so we can show something to the user
if (!this.reversable) {
warning ("Can't undo '%s'", this.description);
return;
}
yield this._undo ();
}
/**
* This the actual implementation of the undo that a subclass needs to
* implement.
*/
protected abstract async void _undo () throws GLib.Error;
}
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