ContractClassAttribute Klasse

Definition

public ref class ContractClassAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Class | System.AttributeTargets.Delegate | System.AttributeTargets.Interface, AllowMultiple=false, Inherited=false)]
[System.Diagnostics.Conditional("DEBUG")]
[System.Diagnostics.Conditional("CONTRACTS_FULL")]
public sealed class ContractClassAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Class | System.AttributeTargets.Delegate | System.AttributeTargets.Interface, AllowMultiple=false, Inherited=false)>]
[<System.Diagnostics.Conditional("DEBUG")>]
[<System.Diagnostics.Conditional("CONTRACTS_FULL")>]
type ContractClassAttribute = class
    inherit Attribute

Public NotInheritable Class ContractClassAttribute
Inherits Attribute

Vererbung

Object

Attribute

ContractClassAttribute

Attribute

AttributeUsageAttribute ConditionalAttribute

Beispiele

Das folgende Beispiel zeigt, wie sie das ContractClassAttribute Attribut verwenden, um anzugeben, dass die Verträge für die IArray Schnittstelle in der IArrayContracts Klasse enthalten sind.

#define CONTRACTS_FULL

using System;
using System.Diagnostics.Contracts;

// An IArray is an ordered collection of objects.
[ContractClass(typeof(IArrayContract))]
public interface IArray
{
    // The Item property provides methods to read and edit entries in the array.
    Object this[int index]
    {
        get;
        set;
    }

    int Count
    {
        get;
    }

    // Adds an item to the list.
    // The return value is the position the new element was inserted in.
    int Add(Object value);

    // Removes all items from the list.
    void 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.
    void Insert(int index, Object value);

    // Removes the item at position index.
    void RemoveAt(int index);
}

[ContractClassFor(typeof(IArray))]
internal abstract class IArrayContract : IArray
{
    int IArray.Add(Object value)
    {
        // Returns the index in which an item was inserted.
        Contract.Ensures(Contract.Result<int>() >= -1);
        Contract.Ensures(Contract.Result<int>() < ((IArray)this).Count);
        return default(int);
    }
    Object IArray.this[int index]
    {
        get
        {
            Contract.Requires(index >= 0);
            Contract.Requires(index < ((IArray)this).Count);
            return default(int);
        }
        set
        {
            Contract.Requires(index >= 0);
            Contract.Requires(index < ((IArray)this).Count);
        }
    }
    public int Count
    {
        get
        {
            Contract.Requires(Count >= 0);
            Contract.Requires(Count <= ((IArray)this).Count);
            return default(int);
        }
    }

    void IArray.Clear()
    {
        Contract.Ensures(((IArray)this).Count == 0);
    }

    void IArray.Insert(int index, Object value)
    {
        Contract.Requires(index >= 0);
        Contract.Requires(index <= ((IArray)this).Count);  // For inserting immediately after the end.
        Contract.Ensures(((IArray)this).Count == Contract.OldValue(((IArray)this).Count) + 1);
    }

    void IArray.RemoveAt(int index)
    {
        Contract.Requires(index >= 0);
        Contract.Requires(index < ((IArray)this).Count);
        Contract.Ensures(((IArray)this).Count == Contract.OldValue(((IArray)this).Count) - 1);
    }
}

#Const CONTRACTS_FULL = True

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


    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


    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
End Class

Hinweise

Typen, die mit diesem Attribut gekennzeichnet sind, weisen Codeverträge auf, die in einem separaten Typ enthalten sind. Der Typ, der die Verträge enthält, wird im Konstruktor angegeben.

Weitere Informationen

• ContractClassForAttribute