Change values in Class Attribute at runtime

Question

If I have a class like this

[Attr("Blah",
 Data = "Blah")]
public class Test : SuperClass{}

Is there a way I can change the values of the attribute of an instance of the class at runtime? eg in pseudo code

SuperClass test = new Test();
test.Attr.Value = "blah1";
test.Attr.Data = "blah2";

(I have an instance of the class I want to change the attributes on, cast as a class it extends)

possible duplicate of Change Attribute's parameter at runtime — Alastair Pitts
– Alastair Pitts, Commented Mar 13, 2013 at 0:39
I've already looked at that, those are method attributes, class attributes seem to be different. At the least that question didn't help me. — UberMouse
– UberMouse, Commented Mar 13, 2013 at 0:51
I'm pretty sure you can change these at runtime as they are embedded into the metadata of the assembly. — sa_ddam213
– sa_ddam213, Commented Mar 13, 2013 at 1:03
I don't want to change them for the class, I only want to change them for the specific instance of the class, you can do this for attributes on Properties afaik, so I was hoping it can be done with class attributes. — UberMouse
– UberMouse, Commented Mar 13, 2013 at 1:04
@UberMouse: The top rated answer in the question i linked is an example the uses class attributes. — Alastair Pitts
– Alastair Pitts, Commented Mar 13, 2013 at 2:21

Roman Gruber · Accepted Answer · 2013-03-13 02:50:55Z

3

There is no implicit connection between attributes and objects instances. Only between the class and the attribute. The best bet would be to look for the attribute in the constructor and "cache" the values in properties on the object. Of course that doesn't make sense if you are only looking at the Test class, but it does make sense if the constructor of the SuperClass looks for the custom attributes on the type retrieved with "this.GetType()".

answered Mar 13, 2013 at 2:50

Roman Gruber

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1 Comment

UberMouse Over a year ago

Not possible then. Oh well.

mmm · Accepted Answer · 2013-11-05 11:49:14Z

-1

You can change Attribute values at runtime at Class level (not object instance level):

var attr = TypeDescriptor.GetProperties(typeof(UserContact))["UserName"].Attributes[typeof(ReadOnlyAttribute)] as ReadOnlyAttribute;
attr.GetType().GetField("isReadOnly", BindingFlags.NonPublic | BindingFlags.Instance).SetValue(attr, username_readonly);

answered Nov 5, 2013 at 11:49

mmm

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1 Comment

d.popov Over a year ago

This is setting the attribute of a property if the class ("UserName"), not on the class ("UserContact"). The question is to set value of a class attribute.

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