ReadOnlyAttribute Class
Important
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Specifies whether the property this attribute is bound to is read-only or read/write. This class cannot be inherited.
public ref class ReadOnlyAttribute sealed : Attribute
[System.AttributeUsage(System.AttributeTargets.All)]
public sealed class ReadOnlyAttribute : Attribute
public sealed class ReadOnlyAttribute : Attribute
[<System.AttributeUsage(System.AttributeTargets.All)>]
type ReadOnlyAttribute = class
inherit Attribute
type ReadOnlyAttribute = class
inherit Attribute
Public NotInheritable Class ReadOnlyAttribute
Inherits Attribute
- Inheritance
- Attributes
The following code example marks a property as read-only.
[ReadOnly(true)]
int get()
{
// Insert code here.
return 0;
}
}
[ReadOnly(true)]
public int MyProperty {
get {
// Insert code here.
return 0;
}
}
Public ReadOnly Property MyProperty() As Integer
Get
' Insert code here.
Return 0
End Get
End Property
The next code example shows how to check the value of the ReadOnlyAttribute for MyProperty
. First, the code gets a PropertyDescriptorCollection with all the properties for the object. Next, it indexes into the PropertyDescriptorCollection to get MyProperty
. Then it returns the attributes for this property and saves them in the attributes variable.
The example presents two different ways of checking the value of the ReadOnlyAttribute. In the second code fragment, the example calls the Equals method. In the last code fragment, the example uses the IsReadOnly property to check the value.
// Gets the attributes for the property.
AttributeCollection^ attributes = TypeDescriptor::GetProperties( this )[ "MyProperty" ]->Attributes;
// Checks to see whether the value of the ReadOnlyAttribute is Yes.
if ( attributes[ ReadOnlyAttribute::typeid ]->Equals( ReadOnlyAttribute::Yes ) )
{
// Insert code here.
}
// This is another way to see whether the property is read-only.
ReadOnlyAttribute^ myAttribute = dynamic_cast<ReadOnlyAttribute^>(attributes[ ReadOnlyAttribute::typeid ]);
if ( myAttribute->IsReadOnly )
{
// Insert code here.
}
// Gets the attributes for the property.
AttributeCollection attributes =
TypeDescriptor.GetProperties(this)["MyProperty"].Attributes;
// Checks to see whether the value of the ReadOnlyAttribute is Yes.
if(attributes[typeof(ReadOnlyAttribute)].Equals(ReadOnlyAttribute.Yes)) {
// Insert code here.
}
// This is another way to see whether the property is read-only.
ReadOnlyAttribute myAttribute =
(ReadOnlyAttribute)attributes[typeof(ReadOnlyAttribute)];
if(myAttribute.IsReadOnly) {
// Insert code here.
}
' Gets the attributes for the property.
Dim attributes As AttributeCollection = _
TypeDescriptor.GetProperties(Me)("MyProperty").Attributes
' Checks to see whether the value of the ReadOnlyAttribute is Yes.
If attributes(GetType(ReadOnlyAttribute)).Equals(ReadOnlyAttribute.Yes) Then
' Insert code here.
End If
' This is another way to see whether the property is read-only.
Dim myAttribute As ReadOnlyAttribute = _
CType(attributes(GetType(ReadOnlyAttribute)), ReadOnlyAttribute)
If myAttribute.IsReadOnly Then
' Insert code here.
End If
If you marked a class with the ReadOnlyAttribute, use the following code example to check the value.
AttributeCollection^ attributes = TypeDescriptor::GetAttributes( MyProperty );
if ( attributes[ ReadOnlyAttribute::typeid ]->Equals( ReadOnlyAttribute::Yes ) )
{
// Insert code here.
}
AttributeCollection attributes =
TypeDescriptor.GetAttributes(MyProperty);
if(attributes[typeof(ReadOnlyAttribute)].Equals(ReadOnlyAttribute.Yes)) {
// Insert code here.
}
Dim attributes As AttributeCollection = TypeDescriptor.GetAttributes(MyProperty)
If attributes(GetType(ReadOnlyAttribute)).Equals(ReadOnlyAttribute.Yes) Then
' Insert code here.
End If
Members that are marked with the ReadOnlyAttribute set to true
or that do not have a Set
method cannot be changed. Members that do not have this attribute or that are marked with the ReadOnlyAttribute set to false
are read/write, and they can be changed. The default is No.
Important
The PropertyDescriptor class enforces the ReadOnlyAttribute in the design environment and at run time. When you mark a property with the ReadOnlyAttribute set to true
, the value of this attribute is set to the constant member Yes. For a property marked with the ReadOnlyAttribute set to false
, the value is No. Therefore, when you want to check the value of this attribute in your code, you must specify the attribute as ReadOnlyAttribute.Yes or ReadOnlyAttribute.No.
For more information, see Attributes.
Read |
Initializes a new instance of the ReadOnlyAttribute class. |
Default |
Specifies the default value for the ReadOnlyAttribute, which is No (that is, the property this attribute is bound to is read/write). This |
No |
Specifies that the property this attribute is bound to is read/write and can be modified. This |
Yes |
Specifies that the property this attribute is bound to is read-only and cannot be modified in the server explorer. This |
Is |
Gets a value indicating whether the property this attribute is bound to is read-only. |
Type |
When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute) |
Equals(Object) |
Indicates whether this instance and a specified object are equal. |
Get |
Returns the hash code for this instance. |
Get |
Gets the Type of the current instance. (Inherited from Object) |
Is |
Determines if this attribute is the default. |
Is |
When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute) |
Match(Object) |
When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute) |
Memberwise |
Creates a shallow copy of the current Object. (Inherited from Object) |
To |
Returns a string that represents the current object. (Inherited from Object) |
_Attribute. |
Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute) |
_Attribute. |
Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute) |
_Attribute. |
Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute) |
_Attribute. |
Provides access to properties and methods exposed by an object. (Inherited from Attribute) |
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 2.0, 2.1 |
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