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ContractClassAttribute Class

Specifies that a separate type contains the code contracts for this type.

System.Object
  System.Attribute
    System.Diagnostics.Contracts.ContractClassAttribute

Namespace:  System.Diagnostics.Contracts
Assembly:  mscorlib (in mscorlib.dll)
'Declaration
<ConditionalAttribute("CONTRACTS_FULL")> _
<ConditionalAttribute("DEBUG")> _
<AttributeUsageAttribute(AttributeTargets.Class Or AttributeTargets.Interface Or AttributeTargets.Delegate, AllowMultiple := False,  _
	Inherited := False)> _
Public NotInheritable Class ContractClassAttribute _
	Inherits Attribute

The ContractClassAttribute type exposes the following members.

  NameDescription
Public methodSupported by Portable Class LibrarySupported in .NET for Windows Store appsContractClassAttributeInitializes a new instance of the ContractClassAttribute class.
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  NameDescription
Public propertySupported by Portable Class LibrarySupported in .NET for Windows Store appsTypeContainingContractsGets the type that contains the code contracts for this type.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodSupported by Portable Class LibrarySupported in .NET for Windows Store appsEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Public methodSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Public methodSupported by Portable Class LibrarySupported in .NET for Windows Store appsToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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Types that are marked with this attribute have code contracts that are included in a separate type. The type that contains the contracts is specified in the constructor.

The following example shows how to use the ContractClassAttribute attribute to specify that the contracts for the IArray interface are contained in the IArrayContracts class.

Imports System
Imports System.Diagnostics.Contracts


' An IArray is an ordered collection of objects.    
<ContractClass(GetType(IArrayContract))> _
Public Interface IArray
    ' The Item property provides methods to read and edit entries in the array. 

    Default Property Item(ByVal index As Integer) As [Object]


    ReadOnly Property Count() As Integer 


    ' Adds an item to the list.   
    ' The return value is the position the new element was inserted in. 
    Function Add(ByVal value As Object) As Integer 

    ' Removes all items from the list. 
    Sub Clear()

    ' Inserts value into the array at position index. 
    ' index must be non-negative and less than or equal to the  
    ' number of elements in the array.  If index equals the number 
    ' of items in the array, then value is appended to the end. 
    Sub Insert(ByVal index As Integer, ByVal value As [Object])


    ' Removes the item at position index. 
    Sub RemoveAt(ByVal index As Integer)
End Interface 'IArray

<ContractClassFor(GetType(IArray))> _
Friend MustInherit Class IArrayContract
    Implements IArray

    Function Add(ByVal value As Object) As Integer Implements IArray.Add
        ' Returns the index in which an item was inserted.
        Contract.Ensures(Contract.Result(Of Integer)() >= -1) '
        Contract.Ensures(Contract.Result(Of Integer)() < CType(Me, IArray).Count) '
        Return 0

    End Function 'IArray.Add

    Default Property Item(ByVal index As Integer) As Object Implements IArray.Item
        Get
            Contract.Requires(index >= 0)
            Contract.Requires(index < CType(Me, IArray).Count)
            Return 0 '
        End Get 
        Set(ByVal value As [Object])
            Contract.Requires(index >= 0)
            Contract.Requires(index < CType(Me, IArray).Count)
        End Set 
    End Property 

    Public ReadOnly Property Count() As Integer Implements IArray.Count
        Get
            Contract.Requires(Count >= 0)
            Contract.Requires(Count <= CType(Me, IArray).Count)
            Return 0 '
        End Get 
    End Property 

    Sub Clear() Implements IArray.Clear
        Contract.Ensures(CType(Me, IArray).Count = 0)

    End Sub 'IArray.Clear


    Sub Insert(ByVal index As Integer, ByVal value As [Object]) Implements IArray.Insert
        Contract.Requires(index >= 0)
        Contract.Requires(index <= CType(Me, IArray).Count) ' For inserting immediately after the end.
        Contract.Ensures(CType(Me, IArray).Count = Contract.OldValue(CType(Me, IArray).Count) + 1)

    End Sub 'IArray.Insert


    Sub RemoveAt(ByVal index As Integer) Implements IArray.RemoveAt
        Contract.Requires(index >= 0)
        Contract.Requires(index < CType(Me, IArray).Count)
        Contract.Ensures(CType(Me, IArray).Count = Contract.OldValue(CType(Me, IArray).Count) - 1)

    End Sub 'IArray.RemoveAt
End Class 'IArrayContract

.NET Framework

Supported in: 4.5.1, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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