A fancy-pants RAII helper class to reduce chances of lag compensation screwups

lagcompensation_raii.cpp

// example RAII class to help ensure that FinishLagCompensation is called upon leaving scope
class CLagCompensatedSection
{
public:
    // start lag compensation upon construction
    CLagCompensatedSection(CBasePlayer *player, CUserCmd *cmd) :
        m_pPlayer(player)
    {
        lagcompensation->StartLagCompensation(player, cmd);
    }
    
    // guaranteed to finish lag compensation upon destruction (when going out of scope)
    ~CLagCompensatedSection()
    {
        lagcompensation->FinishLagCompensation(m_pPlayer);
    }
    
private:
    CBasePlayer m_pPlayer;
};

// only do lag compensation in server simulation code, not client prediction code
#ifndef CLIENT_DLL
#define LAG_COMPENSATED_SECTION(player, cmd) CLagCompensatedSection lagcomp(player, cmd)
#else
#define LAG_COMPENSATED_SECTION(player, cmd)
#endif


////////////////////////////////////////////////////////////////////////////////
// example usage by a hypothetical CTFGizmoGadget weapon ///////////////////////
////////////////////////////////////////////////////////////////////////////////
void CTFGizmoGadget::FireWomboWidget()
{
    CTFPlayer *pOwner = ToTFPlayer(GetOwnerEntity);
    if (!pOwner) return;
    
    LAG_COMPENSATED_SECTION(pOwner, pOwner->GetCurrentCommand());
    // at this point, lagcompensation->StartLagCompensation() has been called
    
    DoHitTraceStuff();
    
    if (MaybeWeShouldntActuallyFireAWidget())
    {
        // by leaving scope, lagcompensation->FinishLagCompensation() will automatically be called
        // (we don't even have to remember to do anything, it just happens because we exit scope)
        return;
    }
    
    ApplyDamageToPlayersWeHit();
    
    // by leaving scope, lagcompensation->FinishLagCompensation() will automatically be called
    // (we don't even have to remember to do anything, it just happens because we exit scope)
}


////////////////////////////////////////////////////////////////////////////////
// another example of potential usage //////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
void CTFGizmoGadget::UseNeatoAttack()
{
    CTFPlayer *pOwner = ToTFPlayer(GetOwnerEntity);
    if (!pOwner) return;
    
    DoStuffThatShouldNotBeLagCompensated();
    
    {
        LAG_COMPENSATED_SECTION(pOwner, pOwner->GetCurrentCommand());
        // at this point, lagcompensation->StartLagCompensation() has been called
        
        DoLagCompensatedStuff();
    }
    // right here, since the CLagCompensatedSection object goes out of scope,
    // lagcompensation->FinishLagCompensation() is automatically called
    
    DoOtherStuffThatShouldNotBeLagCompensated();
}