Some ideas about attribute

[Bsntmnhss]

Add a new keyword "attribute" to create an attribute

For example:

[AttributeUsage(...)]
public attribute MyAttribute
{
    ...
}

It will translate into:

[AttributeUsage(...)]
public class MyAttribute : Attribute
{
    ...
}

Add more attribute targets

Such as "Record" "Attribute" and so on

[Flags]
public enum AttributeTargets
{
    ...
    Record,
    Attribute,
    ...
}

Now the AttributeUsage attribute can become like this:

[AttributeUsage(AttributeTargets.Attribute, Inherited = true)]
public attribute AttributeUsageAttribute
{
    ...
}

Add some attribute event methods

For example:

[AttributeUsage(AttributeTargets.Method)]
public attribute TestMethodAttribute
{
    public override void BeforeInvokeMethod(MethodInfo info, object? sender, object?[]? args ...)
    {
        ...
    }
}


public class Program
{
    [TestMethod]
    static void Test()
    {
        ...
    }
    
    static void Main(string[] args)
    {
        Test(); //Call the "BeforeInvokeMethod" method then call the "Test" method
    }
}

This is an example of "BeforeInvokeMethod" event method
Others (for example, fields and properties have OnGet, OnSet and other event methods)

[YairHalberstadt]

What is the motivation behind these ideas? What is the real world use case where current solutions are insufficient, and these suggestions will help?

[huoyaoyuan]

Add a new keyword "attribute" to create an attribute

Usable, but doesn't solve a lot comparing to current syntax.

Add more attribute targets

Such as "Record"

This is something we intentionally avoided. The team said it should be possible to use non-record code to define a class same to record.

"Attribute"

This is really only meaningful for AttributeUsageAttribute. Since we can't change that attribute, it will be useless at all.

Add some attribute event methods

This are better for a custom code generator recognizing the attribute.