ContractClassAttribute Constructor
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Initializes a new instance of the ContractClassAttribute class.
Namespace: System.Diagnostics.Contracts
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Sub New ( _
typeContainingContracts As Type _
)
public ContractClassAttribute(
Type typeContainingContracts
)
Parameters
- typeContainingContracts
Type: System.Type
The type that contains the code contracts for this type.
Examples
The following example shows how to use the ContractClassAttribute constructor 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 VB.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
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);
}
}
Version Information
Silverlight
Supported in: 5, 4
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.