IPermission.Intersect Method (IPermission)

 

Creates and returns a permission that is the intersection of the current permission and the specified permission.

Namespace:   System.Security
Assembly:  mscorlib (in mscorlib.dll)

Function Intersect (
	target As IPermission
) As IPermission

Parameters

target
Type: System.Security.IPermission

A permission to intersect with the current permission. It must be of the same type as the current permission.

Return Value

Type: System.Security.IPermission

A new permission that represents the intersection of the current permission and the specified permission. This new permission is null if the intersection is empty.

Exception Condition
ArgumentException

The target parameter is not null and is not an instance of the same class as the current permission.

The intersection of two permissions is a permission that describes the set of operations they both describe in common. Only a demand that passes both original permissions will pass the intersection.

The following statements are required to be true for all implementations of the Intersect method. X and Y represent IPermission object references that are not null.

  • X.Intersect(X) returns a value equal to X.

  • X.Intersect(Y) returns the same value as Y.Intersect(X).

  • X.Intersect(null) returns null.

The following code example demonstrates implementing the Intersect method. This code example is part of a larger example provided for the IPermission class.

' Return a new object that contains the intersection of 'this' and 'target'.
Public Overrides Function Intersect(ByVal target As IPermission) As IPermission
    ' If 'target' is null, return null.
    If target Is Nothing Then
        Return Nothing
    End If
    ' Both objects must be the same type.
    Dim soundPerm As SoundPermission = VerifyTypeMatch(target)

    ' If 'this' and 'target' are unrestricted, return a new unrestricted permission.
    If m_specifiedAsUnrestricted AndAlso soundPerm.m_specifiedAsUnrestricted Then
        Return Clone(True, SoundPermissionState.PlayAnySound)
    End If
    ' Calculate the intersected permissions. If there are none, return null.
    Dim val As SoundPermissionState = CType(Math.Min(CType(m_flags, Int32), CType(soundPerm.m_flags, Int32)), SoundPermissionState)
    If val = 0 Then
        Return Nothing
    End If
    ' Return a new object with the intersected permission value.
    Return Clone(False, val)

End Function 'Intersect

.NET Framework
Available since 1.1
Return to top
Show: