Is it possible to change the DescriptionAttribute value of an inherited DependencyProperty in a derived class?

Question

If I create a class that extends UserControl and want to set a default value for a DependencyProperty that is declared in UserControl, say FontSize, I can add a static constructor like the following:

static MyUserControl()
{
    UserControl.FontSizeProperty.OverrideMetadata(typeof(MyUserControl), 
new FrameworkPropertyMetadata(28.0));
}

Before I learned about the OverrideMetadata method, I used to override the property and set the DescriptionAttribute in the following way:

public new static readonly DependencyProperty FontSizeProperty = 
DependencyProperty.Register("FontSize", typeof(double), typeof(MyUserControl), 
new PropertyMetadata(28.0));

[Description("My custom description."), Category("Text")]
public new double FontSize
{
    get { return (double)GetValue(FontSizeProperty); }
    set { SetValue(FontSizeProperty, value); }
}

The DescriptionAttribute value is displayed as a popup tooltip in the Properties Window of Visual Studio when a user moves the mouse pointer over the relevant property name. My question is, is it possible to set the DescriptionAttribute value of this DependencyProperty in a similar way to overriding the metadata? Or will I have to keep the CLR getter/setter property and attribute declaration?

Many thanks in advance.

Are you actually asking whether you can change the value of an Attribute, which is in the current assembly, at runtime? Because if so: no, you cannot do that because the attributes are stored with the metadata in the assembly and remain there, statically. — Abel, Mar 20 '12 at 23:47
@DaveClemmer, please refrain from making pointless edits. Swapping the [tag:dependency-property] tag to [tag:dependency-properties] was a pointless edit and should have been rejected. — Sheridan, Jun 13 '14 at 13:52
@Sheridan, first of all this was done quite a long time ago, second this was part of a tag cleanup effort to reduce duplicate tags and improve search, third by changing the tag back to dependency-property, you have created a duplicate tag again (that someone will probably remove again), and finally you have reduced your score in the dependency-properties tag that is actually being used. — Dave Clemmer, Jun 15 '14 at 14:36

score 3 · Accepted Answer · edited May 23 '17 at 10:28

I found that I could access the DescriptionAttribute value of the inherited type property, but only from an instance constructor and not the static constuctor because I needed a reference to the control object. Also, I could not set it using this method as it was a read only property:

AttributeCollection attributes = 
    TypeDescriptor.GetProperties(this)["FontSize"].Attributes;
DescriptionAttribute attribute = 
    (DescriptionAttribute)attributes[typeof(DescriptionAttribute)];
attribute.Description = "Custom description"; // not possible - read only property

I then discovered that you can't change declared attribute values at run time from these articles:

I will therefore continue to declare the CLR wrapper properties with new DescriptionAttribute values and override the metadata in the static constructor just to set new default values.

Is it possible to change the DescriptionAttribute value of an inherited DependencyProperty in a derived class?

1 Answers1