Add units::power (watts)

[irwiss]

Summary

None

Purpose of change

Implements the power units from #32067 / #31079

Support power units for changes like #61950

Describe the solution

Implement units::power and the following operators:

Left hand	Op	Right hand	Result
units::power	*	time_duration	units::energy
time_duration	*	units::power	units::energy
units::energy	/	time_duration	units::power
units::energy	/	units::power	time_duration

Describe alternatives you've considered

Testing

The patch adds some unit tests in units_test.cpp

Optionally apply the following patch to make a slight test on vehicle_part::epower and some minor deserialization test

  diff --git a/src/veh_interact.cpp b/src/veh_interact.cpp
  index 7e7e1699bf..2df018046c 100644
  --- a/src/veh_interact.cpp
  +++ b/src/veh_interact.cpp
  @@ -3018,11 +3018,11 @@ void veh_interact::display_details( const vpart_info *part )
                           whl ? whl->width : 0 );
       }
   
  -    if( part->epower != 0 ) {
  +    if( part->epower != 0_W ) {
           fold_and_print( w_details, point( col_2, line + 3 ), column_width, c_white,
                           "%s: <color_light_gray>%+4d</color>",
                           small_mode ? _( "Epwr" ) : _( "Electric Power" ),
  -                        part->epower );
  +                        units::to_watt<int64_t>( part->epower ) );
       }
   
       // line 4 [horizontal]: fuel_type (if applicable)
  diff --git a/src/veh_type.cpp b/src/veh_type.cpp
  index aefaaa9c88..2a0be18804 100644
  --- a/src/veh_type.cpp
  +++ b/src/veh_type.cpp
  @@ -947,7 +947,7 @@ void vpart_info::check()
                   debugmsg( "vehicle part %s has undefined tool quality %s", part.id.c_str(), q.first.c_str() );
               }
           }
  -        if( part.has_flag( VPFLAG_ENABLED_DRAINS_EPOWER ) && part.epower == 0 ) {
  +        if( part.has_flag( VPFLAG_ENABLED_DRAINS_EPOWER ) && part.epower == 0_W ) {
               debugmsg( "%s is set to drain epower, but has epower == 0", part.id.c_str() );
           }
           // Parts with non-zero epower must have a flag that affects epower usage
  @@ -957,7 +957,7 @@ void vpart_info::check()
                   "REACTOR", "WIND_TURBINE", "WATER_WHEEL"
               }
           };
  -        if( part.epower != 0 &&
  +        if( part.epower != 0_W &&
           std::none_of( handled.begin(), handled.end(), [&part]( const std::string & flag ) {
           return part.has_flag( flag );
           } ) ) {
  @@ -1020,14 +1020,15 @@ int vpart_info::format_description( std::string &msg, const nc_color &format_col
               continue;
           } else if( flagid == "ENABLED_DRAINS_EPOWER" ||
                      flagid == "ENGINE" ) { // ENGINEs get the same description
  -            if( epower < 0 ) {
  -                append_desc( string_format( json_flag::get( "ENABLED_DRAINS_EPOWER" ).info(), -epower ) );
  +            if( epower < 0_W ) {
  +                append_desc( string_format( json_flag::get( "ENABLED_DRAINS_EPOWER" ).info(),
  +                                            -units::to_watt<int64_t>( epower ) ) );
               }
           } else if( flagid == "ALTERNATOR" ||
                      flagid == "SOLAR_PANEL" ||
                      flagid == "WATER_WHEEL" ||
                      flagid == "WIND_TURBINE" ) {
  -            append_desc( string_format( json_flag::get( flagid ).info(), epower ) );
  +            append_desc( string_format( json_flag::get( flagid ).info(), units::to_watt<int64_t>( epower ) ) );
           } else {
               append_desc( json_flag::get( flagid ).info() );
           }
  diff --git a/src/veh_type.h b/src/veh_type.h
  index fcbb317813..f1e809fabd 100644
  --- a/src/veh_type.h
  +++ b/src/veh_type.h
  @@ -451,7 +451,7 @@ class vpart_info
            * Electrical power, flat rate (watts); positive for generation, negative for consumption
            * For motor consumption scaled with powertrain demand see @ref energy_consumption instead
            */
  -        int epower = 0;
  +        units::power epower = 0_W;
   
           /**
            * Energy consumed per second by engines and motors when delivering max @ref power
  diff --git a/src/vehicle.cpp b/src/vehicle.cpp
  index e9c6c952ae..16e9b9a6ce 100644
  --- a/src/vehicle.cpp
  +++ b/src/vehicle.cpp
  @@ -1105,7 +1105,7 @@ int vehicle::part_vpower_w( const int index, const bool at_full_hp ) const
   // for motor consumption see @ref vpart_info::energy_consumption instead
   int vehicle::part_epower_w( const int index ) const
   {
  -    int e = part_info( index ).epower;
  +    int e = units::to_watt<int>( part_info( index ).epower );
       if( e < 0 ) {
           return e; // Consumers always draw full power, even if broken
       }
  @@ -4723,7 +4723,7 @@ int vehicle::total_accessory_epower_w() const
       for( int part : accessories ) {
           const vehicle_part &vp = parts[part];
           if( vp.enabled ) {
  -            epower += vp.info().epower;
  +            epower += units::to_watt<int64_t>( vp.info().epower );
           }
       }
       return epower;
  @@ -5082,7 +5082,7 @@ void vehicle::power_parts()
   
           for( const vpart_reference &vp : get_enabled_parts( VPFLAG_ENABLED_DRAINS_EPOWER ) ) {
               vehicle_part &pt = vp.part();
  -            if( pt.info().epower < 0 ) {
  +            if( pt.info().epower < 0_W ) {
                   pt.enabled = false;
               }
           }
  @@ -5193,7 +5193,7 @@ int vehicle::traverse_vehicle_graph( Vehicle *start_veh, int amount, Func action
   
               // Add this connected vehicle to the queue of vehicles to search next,
               // but only if we haven't seen this one before (checked above)
  -            int target_loss = current_loss + current_veh->part_info( p ).epower;
  +            int target_loss = current_loss + units::to_watt( current_veh->part_info( p ).epower );
               connected_vehs.push_back( std::make_pair( target_veh, target_loss ) );
               // current_veh could be invalid after this point
   
  @@ -7415,7 +7415,7 @@ void vehicle::update_time( const time_point &update_to )
                   here.emit_field( exhaust_dest( exhaust_part ), e );
               }
           }
  -        discharge_battery( pt.info().epower );
  +        discharge_battery( units::to_watt( pt.info().epower ) );
       }
   
       if( sm_pos.z < 0 ) {
  diff --git a/src/vehicle_part.cpp b/src/vehicle_part.cpp
  index efa5969057..79b70e1c34 100644
  --- a/src/vehicle_part.cpp
  +++ b/src/vehicle_part.cpp
  @@ -689,7 +689,7 @@ bool vehicle::can_enable( const vehicle_part &pt, bool alert ) const
   
       // TODO: check fuel for combustion engines
   
  -    if( pt.info().epower < 0 && fuel_left( fuel_type_battery, true ) <= 0 ) {
  +    if( pt.info().epower < 0_W && fuel_left( fuel_type_battery, true ) <= 0 ) {
           if( alert ) {
               add_msg( m_bad, _( "Insufficient power to enable %s" ), pt.name() );
           }
  -- 
  2.36.1.windows.1
  
  

Additional context

Tagging @Hirmuolio in case you're interested in reviewing