Add Attributes to the generated property

[hutterm]

first of all, great library!!!

Is there a way to put an Attribute on the generated property without having to go through MetadataTypeAttribute on the class?

[canton7]

Thanks! No, there's no support for that currently. It might be worth adding though! What sort of attributes specifically are you thinking of?

Do bear in mind, those attributes will have to be applicable to both fields and properties, and the tooling which uses them will have to know to ignore the attribute that was added to the field.

[hutterm]

hmm, I actually didn't consider that a specific attribute might only be applicable to a property only and not a field.
I just tried wrapping a attribute with another but that doesn't work as attributes only allow simple parameters.
I guess this might not be as easy as I first imagined. just copying the attribute might have unwanted implications

... one more reason to get partial properties in c#

[canton7]

Yet another option is to allow something like:

[inpc: EditorBrowsable(EditorBrowsableState.Never)]
[Notify] private int _foo;

This raises:

warning CS0658: 'inpc' is not a recognized attribute location. Valid attribute locations for this declaration are 'field, property'. All attributes in this block will be ignored.

... but that warning can be squashed (although it might annoy people with specific policies around suppressing warnings). Otherwise it works well: it's exposed nicely through Roslyn, but isn't applied to the field in the generated IL.

[hutterm]

Here's an idea:
could you generate an attribute with the same form as the real attribute in the same namespace as the real one, something like:

    public class Test
    {
        [Notify]
        [Property_EditorBrowsable(EditorBrowsableState.Never)]
        private string _test;
    }
///generated:
namespace System.ComponentModel
{
    public class Property_EditorBrowsableAttribute : Attribute
    {
        public Property_EditorBrowsableAttribute(EditorBrowsableState state)
        {
            State = state;
        }
        public Property_EditorBrowsableAttribute() : this(EditorBrowsableState.Always)
        {  }
        public EditorBrowsableState State { get; }
    }
}

this would make it necessary to have the real namespace using.
not really sure how to discover the namespace though from the point of the generator

but it would allow to map all the same properties and make it look very much like the real attribute

[hutterm]

thinking more about this, I almost think that #21 (reply in thread) would be the nicest and probably easiest option. Though It still has some magic to it and is not discoverable. Concerning naming: I'd almost go for naming it close to notify so you have the connection to the NotifyAttribute. on the other hand inpc: is short...

[canton7]

Yeah, I like that it's neat and you get design-time support, and it mirrors how you'd apply an attribute to a compiler-generated backing field from a property. I don't like that we're forcing a warning onto the user - either they've got to add suppression around that line, or they've got to disable what is quite a useful warning across their whole project.

It's not entirely straightforward to implement either - we'll have to reconstruct the attribute from the parsed data which Roslyn gives us, making sure that everything is fully-qualified. Thankfully the range of ways you can write an attribute is fairly small.

I'm leaning towards the second option tbh. It's clunky, but it's obvious what's going on. Whatever string you use is pasted into the generated code verbatim. Simple. No warnings, no magic.

[hutterm]

Yeah, I think I agree. It would be straightforward.

[canton7]

I've released this as v1.0.5, see the README. Let me know if you have any issues!