Undo System - It's time

[AlexvZyl]

Check at 21:40.

Command pattern Wikipedia.

@UlrichLouwEnerdyne Vir as jy wil inloer hier.

[AlexvZyl]

Command parent class:

class Command
{
public:
    inline virtual void execute() = 0;
    inline virtual void undo() = 0;

protected:
    // We do no want instances of Command.
    inline Command() = default;

private:
    // Children will have data here required for the command.

}

I think having a CommandLog is nice, similarly to how we have an EventLog with events.

class CommandLog
{
public:

    static void undo()
    {
        if(!m_commandHistory.size()) return;
    
        m_commandHistory.back()->undo();
        m_commandHistory.pop_back();
    }
    
    static void log(const Command& command)
    {
        m_commandHistory.push_back(command);
    }
    
    static void execute(Command& command)
    {
        command.execute();
        log(command);
    }

    static const auto& getHistory()
    {
        return m_commandHistory;
    }

private:

    // Probably want to put a max size on this.
    std::vector<std::unique_ptr<Command>> m_commandHistory;
    
    // Do not want an instance.
    inline CommandLog() = default;
}

If we want we can also add wrappers in Application for the log, since the engines would want to use the log.

However, this will require a relatively large rework, since everything that we want to be able to redo has to fit into this. But I think it is worth it.

[Cullen-Enerdyne]

Changes to above:

• Made CommandLog non-static. We will likely log commands per engine.

[AlexvZyl]

Changes to above:

• Made CommandLog non-static. We will likely log commands per engine.

Yes, we definitely want this.