CODEWITHSUNDEEP
c#attributes
caesay
caesay

Reputation: 17233

Attributes creating fields in C#

Alright, so after a few hours of me playing around to no avail, I built a model:

[AttributeUsage(AttributeTargets.All)]
public class PublicAttribute : System.Attribute
{
    public enum Access { Public, Private }
    public PublicAttribute(string Name, Access acs)
    {
    }
    public PublicAttribute(string Name, Access acs, Action get, Action set)
    {
    }
}

So that if somebody were to do something like this:

[Public("PublicProperty", PublicAttribute.Access.Public)]
private string PrivateProperty = "hello";

or 

[Public("PublicProperty", PublicAttribute.Access.Public, ()=>{return PrivateProperty;}, ()=>{PrivateProperty = value})]
private string PrivateProperty = "hello";

and then if somebody was trying to access PrivateProperty, they could just go:

ContainingClass.PublicProperty = //ect

"PublicProperty". and that is because of the attribute, and it would use those get/set accessors.

What I'd like to know:

  1. Is this even possible?
  2. Is there something that already does this?
  3. If its possible, (even if there is something else) How do i do this?

Upvotes: 3

Views: 171

Answers (3)

Chris S
Chris S

Reputation: 65456

Basically no to all 3, as C# is a strongly typed language. Even with duck typing what you're trying to achieve doesn't fit the language.

The attributes you've written allow you to interrogate the properties that have those attributes in the class, but you still need to use Reflection to discover which properties of the attribute class are set. The syntax you want to use is checked at compile-time.

Upvotes: 4

itowlson
itowlson

Reputation: 74832

No, this is not possible using attributes. Properties are part of the class metadata emitted by the C# compiler, and the C# compiler does not consider custom attributes.

You may be able to do this by using a post-processor such as PostSharp, which can rewrite your assembly after the fact, and can be instructed to consider custom attributes. However, you still wouldn't be able to include a delegate in the attribute: the set of types that can be stored in attribute state is extremely limited.

Upvotes: 1

John K
John K

Reputation: 28917

Microsoft made the WebMethodAttribute in a way reminiscent of what you're trying to describe making it represent more permission than C# public, effectively making a method available outside the application domain to the entire Internet (a very global scope). You might read it to get real implementation insight and ideas.

But you're hitting it very simply. You'll have to program some infrastructure to make it work. It's not automatic and you don't have access to Microsoft's source code for all the details.

Upvotes: 0

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