Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Nullable.cs / 1 / Nullable.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== using System; namespace System { using System.Globalization; using System.Reflection; using System.Collections.Generic; using System.Runtime.CompilerServices; using System.Security; // Warning, don't put System.Runtime.Serialization.On*Serializ*Attribute // on this class without first fixing ObjectClone::InvokeVtsCallbacks // Also, because we have special type system support that says a a boxed Nullable// can be used where a boxed is use, Nullable can not implement any intefaces // at all (since T may not). Do NOT add any interfaces to Nullable! // [TypeDependencyAttribute("System.Collections.Generic.NullableComparer`1")] [TypeDependencyAttribute("System.Collections.Generic.NullableEqualityComparer`1")] [Serializable()] public struct Nullable where T : struct { private bool hasValue; internal T value; public Nullable(T value) { this.value = value; this.hasValue = true; } public bool HasValue { get { return hasValue; } } public T Value { get { if (!HasValue) { ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_NoValue); } return value; } } public T GetValueOrDefault() { return value; } public T GetValueOrDefault(T defaultValue) { return HasValue ? value : defaultValue; } public override bool Equals(object other) { if (!HasValue) return other == null; if (other == null) return false; return value.Equals(other); } public override int GetHashCode() { return HasValue ? value.GetHashCode() : 0; } public override string ToString() { return HasValue ? value.ToString() : ""; } public static implicit operator Nullable (T value) { return new Nullable (value); } public static explicit operator T(Nullable value) { return value.Value; } // The following already obsoleted methods were removed: // public int CompareTo(object other) // public int CompareTo(Nullable other) // public bool Equals(Nullable other) // public static Nullable FromObject(object value) // public object ToObject() // public string ToString(string format) // public string ToString(IFormatProvider provider) // public string ToString(string format, IFormatProvider provider) // The following newly obsoleted methods were removed: // string IFormattable.ToString(string format, IFormatProvider provider) // int IComparable.CompareTo(object other) // int IComparable >.CompareTo(Nullable other) // bool IEquatable >.Equals(Nullable other) } [System.Runtime.InteropServices.ComVisible(true)] public static class Nullable { [System.Runtime.InteropServices.ComVisible(true)] public static int Compare (Nullable n1, Nullable n2) where T : struct { if (n1.HasValue) { if (n2.HasValue) return Comparer .Default.Compare(n1.value, n2.value); return 1; } if (n2.HasValue) return -1; return 0; } [System.Runtime.InteropServices.ComVisible(true)] public static bool Equals (Nullable n1, Nullable n2) where T : struct { if (n1.HasValue) { if (n2.HasValue) return EqualityComparer .Default.Equals(n1.value, n2.value); return false; } if (n2.HasValue) return false; return true; } // If the type provided is not a Nullable Type, return null. // Otherwise, returns the underlying type of the Nullable type public static Type GetUnderlyingType(Type nullableType) { if( nullableType == null) { throw new ArgumentNullException("nullableType"); } Type result = null; if( nullableType.IsGenericType && !nullableType.IsGenericTypeDefinition) { // instantiated generic type only Type genericType = nullableType.GetGenericTypeDefinition(); if( genericType == typeof(Nullable<>)) { result = nullableType.GetGenericArguments()[0]; } } return result; } // The following already obsoleted methods were removed: // public static bool HasValue (Nullable value) // public static T GetValueOrDefault (Nullable value) // public static T GetValueOrDefault (Nullable value, T valueWhenNull) // The following newly obsoleted methods were removed: // public static Nullable FromObject (object value) // public static object ToObject (Nullable value) // public static object Wrap(object value, Type type) // public static object Unwrap(object value) } }
Link Menu

This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- ObjectListFieldsPage.cs
- FormViewActionList.cs
- BitmapSourceSafeMILHandle.cs
- WindowsStatic.cs
- WebBrowserNavigatingEventHandler.cs
- BackoffTimeoutHelper.cs
- KeyboardDevice.cs
- StylusPointPropertyUnit.cs
- OptimizedTemplateContent.cs
- XmlAttributeOverrides.cs
- RotationValidation.cs
- ApplicationDirectory.cs
- GlobalItem.cs
- InputReferenceExpression.cs
- ClientType.cs
- WebConfigurationHost.cs
- Camera.cs
- EventLogger.cs
- HandlerBase.cs
- WebPartMinimizeVerb.cs
- SchemaTableColumn.cs
- FormattedTextSymbols.cs
- X509Utils.cs
- DependencyProperty.cs
- ProcessModelInfo.cs
- ToolStripEditorManager.cs
- ComboBox.cs
- PerformanceCounterManager.cs
- PropertyNames.cs
- GlobalItem.cs
- MsmqIntegrationBinding.cs
- PageThemeBuildProvider.cs
- DataGridClipboardCellContent.cs
- _DomainName.cs
- StructuralObject.cs
- ServiceModelSecurityTokenRequirement.cs
- ConnectionInterfaceCollection.cs
- ProxyGenerator.cs
- ComponentGuaranteesAttribute.cs
- Model3DGroup.cs
- WindowsSpinner.cs
- WebPartConnectionsCancelEventArgs.cs
- _LocalDataStore.cs
- VideoDrawing.cs
- Int16.cs
- ActivityCollectionMarkupSerializer.cs
- ResourceSet.cs
- DefaultClaimSet.cs
- Dump.cs
- DrawingGroup.cs
- unitconverter.cs
- SafeViewOfFileHandle.cs
- HtmlTable.cs
- XmlBinaryReader.cs
- DataContext.cs
- ToolZone.cs
- TypeLoadException.cs
- SessionIDManager.cs
- SpeechSynthesizer.cs
- Transform3DGroup.cs
- PrintPageEvent.cs
- OperandQuery.cs
- AmbiguousMatchException.cs
- SettingsSection.cs
- ErrorFormatterPage.cs
- Expressions.cs
- InvalidProgramException.cs
- TableCellCollection.cs
- SamlAssertionKeyIdentifierClause.cs
- XmlSchemaInclude.cs
- SpellerHighlightLayer.cs
- ParameterCollection.cs
- CopyAttributesAction.cs
- ScrollBar.cs
- AsymmetricKeyExchangeDeformatter.cs
- MultipartContentParser.cs
- XmlDocumentSerializer.cs
- IndexerNameAttribute.cs
- CFGGrammar.cs
- HintTextConverter.cs
- LayoutDump.cs
- login.cs
- BigIntegerStorage.cs
- CodeAccessPermission.cs
- VirtualPathExtension.cs
- DbQueryCommandTree.cs
- XmlStringTable.cs
- EntityProviderServices.cs
- PenThreadWorker.cs
- LoginCancelEventArgs.cs
- ping.cs
- XmlHierarchicalEnumerable.cs
- SafeFileHandle.cs
- EdmProviderManifest.cs
- InputReport.cs
- ComboBoxRenderer.cs
- TemplateModeChangedEventArgs.cs
- FamilyTypefaceCollection.cs
- DataGridRowDetailsEventArgs.cs
- OleDbConnectionPoolGroupProviderInfo.cs