C# Language Specification

9.Namespaces 284

9.1Compilation units 284

9.2Namespace declarations 284

9.3Extern aliases 285

9.4Using directives 286

9.4.1Using alias directives 287

9.4.2Using namespace directives 289

9.5Namespace members 291

9.6Type declarations 291

9.7Namespace alias qualifiers 292

9.7.1Uniqueness of aliases 293

10.Classes 295

10.1Class declarations 295

10.1.1Class modifiers 295

10.1.1.1Abstract classes 295

10.1.1.2Sealed classes 296

10.1.1.3Static classes 296

10.1.2Partial modifier 297

10.1.3Type parameters 297

10.1.4Class base specification 298

10.1.4.1Base classes 298

10.1.4.2Interface implementations 299

10.1.5Type parameter constraints 300

10.1.6Class body 304

10.2Partial types 304

10.2.1Attributes 304

10.2.2Modifiers 305

10.2.3Type parameters and constraints 305

10.2.4Base class 305

10.2.5Base interfaces 306

10.2.6Members 306

10.2.7Partial methods 307

10.2.8Name binding 309

10.3Class members 310

10.3.1The instance type 311

10.3.2Members of constructed types 311

10.3.3Inheritance 312

10.3.4The new modifier 313

10.3.5Access modifiers 313

10.3.6Constituent types 313

10.3.7Static and instance members 313

10.3.8Nested types 314

10.3.8.1Fully qualified name 315

10.3.8.2Declared accessibility 315

10.3.8.3Hiding 316

10.3.8.4this access 316

10.3.8.5Access to private and protected members of the containing type 317

10.3.8.6Nested types in generic classes 318

10.3.9Reserved member names 319

10.3.9.1Member names reserved for properties 319

10.3.9.2Member names reserved for events 320

10.3.9.3Member names reserved for indexers 320

10.3.9.4Member names reserved for destructors 320

10.4Constants 320

10.5Fields 322

10.5.1Static and instance fields 323

10.5.2Readonly fields 324

10.5.2.1Using static readonly fields for constants 324

10.5.2.2Versioning of constants and static readonly fields 324

10.5.3Volatile fields 325

10.5.4Field initialization 326

10.5.5Variable initializers 327

10.5.5.1Static field initialization 327

10.5.5.2Instance field initialization 329

10.6Methods 329

10.6.1Method parameters 331

10.6.1.1Value parameters 333

10.6.1.2Reference parameters 333

10.6.1.3Output parameters 334

10.6.1.4Parameter arrays 335

10.6.2Static and instance methods 338

10.6.3Virtual methods 338

10.6.4Override methods 340

10.6.5Sealed methods 342

10.6.6Abstract methods 343

10.6.7External methods 344

10.6.8Partial methods 345

10.6.9Extension methods 345

10.6.10Method body 346

10.6.11Method overloading 347

10.7Properties 347

10.7.1Static and instance properties 348

10.7.2Accessors 348

10.7.3Automatically implemented properties 353

10.7.4Accessibility 354

10.7.5Virtual, sealed, override, and abstract accessors 355

10.8Events 357

10.8.1Field-like events 359

10.8.2Event accessors 360

10.8.3Static and instance events 362

10.8.4Virtual, sealed, override, and abstract accessors 362

10.9Indexers 362

10.9.1Indexer overloading 366

10.10Operators 366

10.10.1Unary operators 368

10.10.2Binary operators 369

10.10.3Conversion operators 369

10.11Instance constructors 371

10.11.1Constructor initializers 372

10.11.2Instance variable initializers 373

10.11.3Constructor execution 373

10.11.4Default constructors 375

10.11.5Private constructors 376

10.11.6Optional instance constructor parameters 376

10.12Static constructors 376

10.13Destructors 379

10.14Iterators 380

10.14.1Enumerator interfaces 381

10.14.2Enumerable interfaces 381

10.14.3Yield type 381

10.14.4Enumerator objects 381

10.14.4.1The MoveNext method 381

10.14.4.2The Current property 383

10.14.4.3The Dispose method 383

10.14.5Enumerable objects 383

10.14.5.1The GetEnumerator method 384

10.14.6Implementation example 384

10.15Async Functions 390

10.15.1Evaluation of a task-returning async function 391

10.15.2Evaluation of a void-returning async function 391