讀書筆記：CLR var C# 第13章
阿新 • • 發佈：2018-04-01
iconv gui 兩個 命名 ace class where 不同 window
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 6 namespace ClrVarCSharp.C13Interface 7 { 8 class Program 9 { 10 public static void Main(string[] args) 11 { 12 //Test1(); 13 //Test2();14 //Test3(); 15 //Test4(); 16 //Test5(); 17 //Test6(); 18 //A.Test7(); 19 //B.Test7(); 20 //B.Test8(); 21 //Test9(); 22 //C.Test10(); 23 //D.Test10(); 24 //E.Test10(); 25 }26 27 //接口： 28 //對一組方法簽名進行了統一命名 29 //定義了在類型之間進行溝通的標準方式 30 31 //13.3 接口定義和實現 32 //定義接口（該定義已包含在FCL中） 33 //public interface IComparable<in T> // in 逆變量，即允許 object -> string 34 //{ 35 // int CompareTo(T other); 36 //} 37 38 //實現接口 39 public sealed class Point : IComparable<Point> 40 { 41 private int m_x, m_y; 42 public Point(int x, int y) 43 { 44 m_x = x; 45 m_y = y; 46 } 47 //1). 必須標記為public 48 //2). 編譯器總是將其標記為virtual，但派生類不能重寫sealed類的接口方法 49 //3). 但派生類可以重寫繼承同一接口，並為接口方法提供自己的實現 50 //IL代碼：.method public final hidebysig newslot virtual 51 public int CompareTo(Point other) 52 { 53 return Math.Sign(Math.Sqrt(m_x * m_x + m_y * m_y) - 54 Math.Sqrt(other.m_x * other.m_x + other.m_y * other.m_y)); 55 } 56 } 57 58 //13.5 顯示/隱式實現接口 59 60 internal sealed class SimpleType : IDisposable 61 { 62 //隱式實現接口 63 public void Dispose() 64 { 65 Console.WriteLine("Public Dispose"); 66 } 67 //顯示實現接口，不能定義訪問修飾符，總是private 68 //IL代碼：.method private final hidebysig newslot virtual 69 void IDisposable.Dispose() 70 { 71 Console.WriteLine("IDisposable Dispose"); 72 } 73 } 74 static void Test1() 75 { 76 SimpleType st = new SimpleType(); 77 st.Dispose(); 78 IDisposable d = st; 79 d.Dispose(); //若為顯示實現接口，結果為 Public Dispose 80 } 81 82 //13.6 泛型接口 83 84 //非泛型接口 85 static void Test2() 86 { 87 int x = 1, y = 2; 88 IComparable c = x; 89 c.CompareTo(y); //發生裝箱 90 //c.CompareTo("2"); //運行時異常 91 } 92 //泛型接口 93 static void Test3() 94 { 95 int x = 1, y = 2; 96 IComparable<int> c = x; 97 c.CompareTo(y); //不發生裝箱 98 //c.CompareTo("2"); //編譯錯誤 99 } 100 101 //實現同一個接口的多個泛型版本 102 public sealed class Number : IComparable<int>, IComparable<string> 103 { 104 private int m_val = 5; 105 public int CompareTo(int other) 106 { 107 return m_val.CompareTo(other); 108 } 109 public int CompareTo(string other) 110 { 111 return m_val.CompareTo(other); 112 } 113 } 114 115 //13.7 約束方法的參數類型為實現指定接口的類型 116 static void Test4() 117 { 118 int x = 5; 119 Guid g = new Guid(); 120 M(x); //int 同時實現了 IComparable 和 IConvertible 121 //M(g); //編譯錯誤，guid沒有實現IConvertible 122 } 123 static int M<T>(T t) where T : IComparable, IConvertible 124 { 125 return 0; 126 } 127 128 //13.8 一個類實現不同接口的重簽名方法 129 //1). 定義接口 130 public interface IWindow 131 { 132 object GetMenu(); 133 } 134 public interface IRestaurant 135 { 136 object GetMenu(); 137 } 138 //2). 隱式實現接口 139 public sealed class MarioPizzeria : IWindow, IRestaurant 140 { 141 public object GetMenu() //書中“必須使用顯式接口方法實現”說法是錯誤的，可同時實現兩個接口！ 142 { 143 Console.WriteLine("0"); 144 return "0"; 145 } 146 } 147 static void Test5() 148 { 149 MarioPizzeria mp = new MarioPizzeria(); 150 mp.GetMenu(); 151 IWindow window = mp; 152 window.GetMenu(); 153 IRestaurant restaurant = mp; 154 restaurant.GetMenu(); 155 } 156 //3). 顯式實現接口 157 public sealed class MarioPizzeria2 : IWindow, IRestaurant 158 { 159 public object GetMenu() 160 { 161 Console.WriteLine("0"); 162 return "0"; 163 } 164 object IWindow.GetMenu() 165 { 166 Console.WriteLine("1"); 167 return "1"; 168 } 169 object IRestaurant.GetMenu() 170 { 171 Console.WriteLine("2"); 172 return "2"; 173 } 174 } 175 static void Test6() 176 { 177 MarioPizzeria2 mp = new MarioPizzeria2(); 178 mp.GetMenu(); //GetMenu()只是該類的一個普通方法，若未實現則出現編譯錯誤 179 IWindow window = mp; 180 window.GetMenu(); 181 IRestaurant restaurant = mp; 182 restaurant.GetMenu(); 183 } 184 185 //13.9 用顯式接口方法實現來增強編譯時類型安全 186 //原理是顯式實現接口只能“顯式”調用 187 //1). 隱式實現接口可能發生裝箱和運行時異常 188 class A 189 { 190 public interface IComparable1 191 { 192 int CompareTo(object other); 193 } 194 struct SomeValueType : IComparable1 195 { 196 private int m_x; 197 public SomeValueType(int x) { m_x = x; } 198 public int CompareTo(object other) 199 { 200 return m_x - ((SomeValueType)other).m_x; 201 } 202 } 203 public static void Test7() 204 { 205 SomeValueType v = new SomeValueType(0); 206 object o = new object(); 207 int n = v.CompareTo(v); //裝箱 SomeValueType -> Object 208 //n = v.CompareTo(o); //運行時異常 209 } 210 } 211 //2). 顯式實現接口不發生裝箱和編譯時類型安全 212 class B 213 { 214 public interface IComparable1 215 { 216 int CompareTo(object other); 217 } 218 struct SomeValueType : IComparable1 219 { 220 private int m_x; 221 public SomeValueType(int x) { m_x = x; } 222 public int CompareTo(SomeValueType other) 223 { 224 return m_x - other.m_x; 225 } 226 int IComparable1.CompareTo(object other) 227 { 228 return CompareTo((SomeValueType)other); 229 } 230 } 231 public static void Test7() 232 { 233 SomeValueType v = new SomeValueType(0); 234 object o = new object(); 235 int n = v.CompareTo(v); //不發生裝箱 236 //n = v.CompareTo(o); //編譯錯誤，因為顯式接口只能顯式調用 237 } 238 //3). 重新發生裝箱和運行時異常 239 public static void Test8() 240 { 241 SomeValueType v = new SomeValueType(0); 242 IComparable1 c = v; //裝箱 struct -> 引用類型 243 object o = new object(); 244 int n = c.CompareTo(v); //裝箱 引用類型 -> object 245 //n = c.CompareTo(o); //編譯異常 246 } 247 } 248 249 //13.10 顯式實現接口缺陷 250 public static void Test9() 251 { 252 int x = 5; 253 //1). In32顯式實現了IConvertible接口，但此處沒有相關幫助 254 //Single s = x.ToSingle(null); 255 //2). Int32值型轉換為IConvertible發生裝箱 256 Single s = ((IConvertible)x).ToSingle(null); 257 } 258 class C 259 { 260 public static void Test10() 261 { 262 var d1 = new Derived(); 263 var d2 = new Derived(); 264 d1.CompareTo(d2); 265 } 266 internal class Base : IComparable 267 { 268 int IComparable.CompareTo(object obj) 269 { 270 Console.WriteLine("Base‘s CompareTo"); 271 return 0; 272 } 273 } 274 internal sealed class Derived : Base, IComparable 275 { 276 public int CompareTo(object o) 277 { 278 Console.WriteLine("Derived‘s CompareTo"); 279 280 //沒有CompareTo方法 281 //base.CompareTo(o); 282 283 //IComparable c = this; //this實現了IComparable接口 284 //c.CompareTo(o); //所以此處在調用自身導致無窮遞歸 285 286 return 0; 287 } 288 } 289 } 290 class D 291 { 292 public static void Test10() 293 { 294 var d1 = new Derived(); 295 var d2 = new Derived(); 296 d1.CompareTo(d2); 297 } 298 internal class Base : IComparable 299 { 300 int IComparable.CompareTo(object obj) 301 { 302 Console.WriteLine("Base‘s CompareTo"); 303 return 0; 304 } 305 } 306 internal sealed class Derived : Base/*, IComparable*/ 307 { 308 public int CompareTo(object o) 309 { 310 Console.WriteLine("Derived‘s CompareTo"); 311 312 //沒有CompareTo方法 313 //base.CompareTo(o); 314 315 //調用顯式接口方法 316 IComparable c = this; 317 c.CompareTo(o); 318 319 return 0; 320 } 321 } 322 } 323 class E 324 { 325 public static void Test10() 326 { 327 var d1 = new Derived(); 328 var d2 = new Derived(); 329 d1.CompareTo(d2); 330 } 331 internal class Base : IComparable 332 { 333 int IComparable.CompareTo(object obj) 334 { 335 Console.WriteLine("Base‘s CompareTo"); 336 return 0; 337 } 338 public virtual int CompareTo(object o) 339 { 340 Console.WriteLine("Base‘s virtual CompareTo"); 341 return 0; 342 } 343 } 344 internal sealed class Derived : Base, IComparable 345 { 346 public override int CompareTo(object o) 347 { 348 Console.WriteLine("Derived‘s CompareTo"); 349 //此處調用的是虛方法，而非接口的顯式實現方法 350 return base.CompareTo(o); 351 } 352 } 353 } 354 355 } 356 }
讀書筆記：CLR var C# 第13章