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IPermission.Union Method

Creates a permission that is the union of the current permission and the specified permission.

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

IPermission Union (
	IPermission target
)
IPermission Union (
	IPermission target
)
function Union (
	target : IPermission
) : IPermission
Not applicable.

Parameters

target

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

Return Value

A new permission that represents the union of the current permission and the specified permission.

Exception typeCondition

ArgumentException

The target parameter is not a null reference (Nothing in Visual Basic) and is not of the same type as the current permission.

The result of a call to Union is a permission that represents all the operations represented by both the current permission and the specified permission. Any demand that passes either permission passes their union.

The following statements are required to be true for all implementations of the Union method. X and Y represent IPermission objects that are not a null reference (Nothing in Visual Basic).

  • X.Union(X) returns an object that has the same value as X.

  • X.Union(Y) returns an object that has the same value as the object returned by Y.Union(X).

  • X.Union(a null reference (Nothing in Visual Basic)) returns an object that has the same value as X.

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

// Return a new object that contains the union of 'this' and 'target'.
// Note: You do not have to implement this method. If you do not, the version
// in CodeAccessPermission does this:
//    1. If target is not null, a NotSupportedException is thrown.
//    2. If target is null, then Copy is called and the new object is returned.
public override IPermission Union(IPermission target) 
{
    // If 'target' is null, then return a copy of 'this'.
    if (target == null) return Copy();

    // Both objects must be the same type.
    SoundPermission soundPerm = VerifyTypeMatch(target);

    // If 'this' or 'target' are unrestricted, return a new unrestricted permission.
    if (m_specifiedAsUnrestricted || soundPerm.m_specifiedAsUnrestricted)
        return Clone(true, SoundPermissionState.PlayAnySound);

    // Return a new object with the calculated, unioned permission value.
    return Clone(false, (SoundPermissionState)
        Math.Max((Int32) m_flags, (Int32) soundPerm.m_flags));
}

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0
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