HelloWorld.ActionDescriptor.TryStartAt C# (CSharp) Method

        protected virtual PlaceActing TryStartAt( GamePlayer player, Place place )
        {
            lock ( place )
              {
            if ( place.Acting != null )
              throw new InvalidOperationException( "土地上已经存在一个正在进行的活动" );

            if ( Requirement.TryInvest( place ) == false )
              return null;
              }

              return PlaceActing.StartAt( player, place, this );
        }