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FileIOPermission.Union Method

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

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

public override IPermission Union (
	IPermission other
)
public IPermission Union (
	IPermission other
)
public override function Union (
	other : IPermission
) : IPermission
Not applicable.

Parameters

other

A permission to combine with the current permission. It must be 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 other 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 code example shows the behavior of the Union method. This example is part of a larger example provided for the FileIOPermission class.

NoteNote:

The code example is intended to show the behavior of the method, not to demonstrate its use. In general, the methods of permission classes are used by the security infrastructure; they are not typically used in applications.

private bool UnionDemo()
{

    bool returnValue = true;

    string fileIO1, fileIO2;
    FileIOPermission fileIOPerm1, fileIOPerm2;
    IPermission fileIOPerm3;

    FileIOGenerator fileIOGen1 = new FileIOGenerator();
    FileIOGenerator fileIOGen2 = new FileIOGenerator();

    fileIOGen1.ResetIndex();
    while (fileIOGen1.CreateFilePath( out fileIO1 ))
    {
        if (fileIO1 == "")
            fileIOPerm1 = new FileIOPermission(PermissionState.None);
        else
        fileIOPerm1 = new FileIOPermission(FileIOPermissionAccess.Read, fileIO1);
        if (fileIO1 == null) continue;

        Console.WriteLine("**********************************************************\n");
        fileIOGen2.ResetIndex();

        while (fileIOGen2.CreateFilePath( out fileIO2 ))
        {
            if (fileIO2 == "")
                fileIOPerm2 = new FileIOPermission(PermissionState.None);
            else
                fileIOPerm2 = new FileIOPermission(FileIOPermissionAccess.Read, fileIO2);
            try
            {
                string firstPermission = fileIO1 == "" | fileIO1 == null ? "null" : fileIO1;
                string secondPermission = fileIO2 == "" | fileIO2 == null ? "null" : fileIO2;
                fileIOPerm3 = (FileIOPermission)fileIOPerm1.Union(fileIOPerm2);
                fileIOPerm3 = fileIOPerm1.Union(fileIOPerm2);

                if (fileIOPerm3 == null)
                {
                    Console.WriteLine("The union of " + firstPermission + " and " + secondPermission + " is null.");
                }
                else
                {
                    Console.WriteLine("The union of " + firstPermission + " and " + secondPermission +
                        " = \n\t" + ((FileIOPermission)fileIOPerm3).GetPathList(FileIOPermissionAccess.Read)[0]);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine("An exception was thrown for union " + e);
                returnValue = false;
            }

        }

    }

    return returnValue;

}

// Union creates a new permission that is the union of the current 
// permission and the specified permission.
private boolean UnionDemo() 
{
    boolean returnValue = true;
    String fileIO1[] = new String[1];
    String fileIO2[] = new String[1];
    FileIOPermission fileIOPerm1[] = new FileIOPermission[1];
    FileIOPermission fileIOPerm2[] = new FileIOPermission[1];
    
    IPermission fileIOPerm3;
    
    FileIOGenerator fileIOGen1 =  new FileIOGenerator();
    FileIOGenerator fileIOGen2 =  new FileIOGenerator();
    
    fileIOGen1.ResetIndex();
    while(fileIOGen1.CreateFilePath(fileIOPerm1, 
        fileIO1, FileIOPermissionAccess.Read)) {
        if (fileIO1[0] == null) {
            continue ;
        }
        Console.WriteLine("*****************************" 
            + "*****************************\n");
        fileIOGen2.ResetIndex();
        
        while(fileIOGen2.CreateFilePath(fileIOPerm2, 
            fileIO2, FileIOPermissionAccess.Read)) {
            try {
                if (fileIOPerm2[0] == null) {
                    continue ;
                }
                
                String firstPermission = (fileIO1[0].equals("")==
                    true | fileIO1[0] == null) ? "null" : fileIO1[0];
                String secondPermission = (fileIO2[0].equals("") == 
                    true | fileIO2[0] == null) ? "null" : fileIO2[0];
                fileIOPerm3 =((FileIOPermission)(fileIOPerm1[0].
                    Union(fileIOPerm2[0])));
                fileIOPerm3 = fileIOPerm1[0].Union(fileIOPerm2[0]);
                
                if (fileIOPerm3 == null) {
                    Console.WriteLine(("The union of " 
                        + firstPermission + " and " 
                        + secondPermission 
                        + " is null."));
                }
                else {
                    Console.WriteLine(("The union of " + firstPermission 
                        + " and " + secondPermission + " = \n\t" 
                        + ((FileIOPermission)(fileIOPerm3)).
                        GetPathList(FileIOPermissionAccess.Read).
                        get_Item( 0)));
                }
            }
            catch(System.Exception e) {
                Console.WriteLine(("An exception was " 
                    + "thrown for union " + e));
                returnValue = false;
            }
        }
    }
    return returnValue ;
} //UnionDemo    

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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