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
- AffineTransform3D.cs
- SafePEFileHandle.cs
- BatchStream.cs
- SqlVersion.cs
- NonParentingControl.cs
- StylusCollection.cs
- _NetRes.cs
- AudioDeviceOut.cs
- RadioButton.cs
- ExtenderControl.cs
- Compilation.cs
- Rotation3DKeyFrameCollection.cs
- SqlColumnizer.cs
- MonthCalendar.cs
- PropertyChangeTracker.cs
- FontWeight.cs
- VarRefManager.cs
- TabRenderer.cs
- DataServiceHostFactory.cs
- WindowHideOrCloseTracker.cs
- SafeRightsManagementQueryHandle.cs
- PointConverter.cs
- UserPreferenceChangedEventArgs.cs
- GeneralTransformGroup.cs
- SqlInternalConnectionSmi.cs
- TraceContextEventArgs.cs
- CalendarDay.cs
- WizardPanel.cs
- coordinatorfactory.cs
- WindowsEditBox.cs
- MediaEntryAttribute.cs
- ValidatingReaderNodeData.cs
- CookielessHelper.cs
- StringConcat.cs
- ButtonFlatAdapter.cs
- RenderCapability.cs
- RenderDataDrawingContext.cs
- LongPath.cs
- Gdiplus.cs
- FixedFindEngine.cs
- ManipulationVelocities.cs
- Decimal.cs
- Signature.cs
- CodeValidator.cs
- HttpServerVarsCollection.cs
- ContractComponent.cs
- DynamicMethod.cs
- DesignerRegionCollection.cs
- SeverityFilter.cs
- HttpPostedFile.cs
- ReturnEventArgs.cs
- OdbcDataReader.cs
- ImageAttributes.cs
- SpecularMaterial.cs
- SafeRegistryHandle.cs
- HttpResponseInternalWrapper.cs
- IISMapPath.cs
- SimpleBitVector32.cs
- SerializationInfoEnumerator.cs
- CheckedPointers.cs
- LogEntryUtils.cs
- GeneralTransform2DTo3D.cs
- WebBrowserEvent.cs
- CaseCqlBlock.cs
- AsymmetricCryptoHandle.cs
- NullRuntimeConfig.cs
- SecurityTokenResolver.cs
- GeneralTransform.cs
- OracleRowUpdatedEventArgs.cs
- ContentElementAutomationPeer.cs
- TimeSpanValidatorAttribute.cs
- StringArrayConverter.cs
- SequentialWorkflowRootDesigner.cs
- ClientWindowsAuthenticationMembershipProvider.cs
- ActivationService.cs
- OciLobLocator.cs
- TraceListener.cs
- SuppressedPackageProperties.cs
- FontEmbeddingManager.cs
- WS2007FederationHttpBindingElement.cs
- File.cs
- ObjectDataSourceEventArgs.cs
- SoapTypeAttribute.cs
- OleDbException.cs
- Matrix3D.cs
- DSACryptoServiceProvider.cs
- CustomErrorCollection.cs
- ContractMapping.cs
- ValidationManager.cs
- ObjectDataSourceView.cs
- EditingCoordinator.cs
- RequestUriProcessor.cs
- TraceHandlerErrorFormatter.cs
- UInt16Storage.cs
- ImportCatalogPart.cs
- CreateInstanceBinder.cs
- DataControlFieldHeaderCell.cs
- DirectoryObjectSecurity.cs
- Win32.cs
- DockPanel.cs