c# - Set properties of an object to be relative to another property of the same object -

i have method detects collision between ball , left paddle in classic game "pong". have made variables different parts of ball , paddle, in order make collision detection method easier understand. here method (and work).

public bool detectballpaddle1collision() {              var ballbottom = _ball.y + ball.width;             var balltop = _ball.y;             var ballleft = _ball.x;             var ballright = _ball.x + ball.width;             var paddle1bottom = _paddle1.y + paddle.height;             var paddle1top = _paddle1.y;             var paddle1left = playerpaddle.x;             var paddle1right = playerpaddle.x + paddle.width;              if (balltop < paddle1bottom &&                 ballbottom > paddle1top &&                 ballleft < paddle1right) {                 return true;             } else {                 return false;             }         } 

i refactor this, have variables different parts of ball, in ball class, so:

namespace pong.core.models {     public abstract class ball : iball     {         public int y { get; set; }         public int x { get; set; }         public int vx { get; set; }         public int vy { get; set; }         public static int width;         public static int speed;         public int bottom { get; set; }         public int top { get; set; }         public int left { get; set; }         public int right { get; set; }          public ball() {             this.setdirection ("left");             bottom = y + ball.width;             top = y;             left = x;             right = x + ball.width;         } 

which enables me change ball/paddle1 collision detection method this:

public bool detectballpaddle1collision() {              var paddle1bottom = _paddle1.y + paddle.height;             var paddle1top = _paddle1.y;             var paddle1left = playerpaddle.x;             var paddle1right = playerpaddle.x + paddle.width;              if (_ball.top < paddle1bottom &&                 _ball.bottom > paddle1top &&                 _ball.left < paddle1right) {                 return true;             } else {                 return false;             }         } 

theoretically should work, doesn't, ball goes through paddle. should work because property method, , supposed keep updating if relative property, correct? why made ball.bottom, .top, .left , .right, properties getters , setters rather fields not keep updating.

when specify properties { get; set; } happens compiler creating private field , keeps property value in it.

setting top property value y in constructor put initial value of y private field , value never updated y changes.

instead, implement properties this:

(this work assuming x , y being updated during game)

public class ball : iball {     public int y { get; set; }     public int x { get; set; }     public int vx { get; set; }     public int vy { get; set; }     public static int width;     public static int speed;      public int top     {                 {             return y;          }     }      public int left     {                 {             return x;         }     }      public int right     {                 {             return x + ball.width;         }     }      public int bottom     {                 {             return y + ball.width;         }     } }