CODEWITHSUNDEEP
vb.netattributes
Tao Gómez Gil
Tao Gómez Gil

Reputation: 2695

Use one attribute with state or two attributes without state

I'm starting to learn about custom attributes and I have one question for the more experienced users:

I want to mark my properties as "TypeA" or "TypeB" with attributes, so I can check them with reflection. Is it better to have only one attribute with state, like this:

Public Class FlavourAttribute
Inherits Attribute

Private _flavour As Flavours

Public ReadOnly Property Flavour() As Flavours
    Get
        Return _flavour
    End Get
End Property

Public Enum Flavours
    Sweet = 0
    Acid = 1
End Enum

Public Sub New(ByVal flavour As Flavours)
    _flavour = flavour
End Sub

End Class

Or is it better to use two attributes without state:

Public Class SweetAttribute
    Inherits Attribute
End Class

Public Class AcidAttribute
    Inherits Attribute
End Class

I'm asking about drawbacks of these two approaches, or possible alternatives.

Thanks!

Upvotes: 0

Views: 69

Answers (2)

Tao Gómez Gil
Tao Gómez Gil

Reputation: 2695

After a while of playing with custom attributes I would say I've discovered a good reason to prefer separate attributes over one single attribute with state: it is far more simple and readable to check if one property has a single attribute than checking a property of the attribute.

Following with the example in the question, with separate attributes, we would have:

For Each prop As PropertyInfo In MyTipe.GetProperties
    thePropertyIsSweet= Attribute.IsDefined(prop , GetType(SweetAttribute))
    thePropertyIsAcid= Attribute.IsDefined(prop , GetType(AcidAttribute))
Next

While with a single attribute with state I should first check if the property has it, then cast an attribute object from it and retrieve its two properties.

I'm a wrong with this reasoning?

Upvotes: 0

Adam Robinson
Adam Robinson

Reputation: 185623

There's not an answer to your general question, but the answer to your specific question would be to use the latter. Whether or not something is sweet is independent of whether or not it's acidic, so you're talking about different things. If, on the other hand, you were dealing with related (or mutually exclusive) properties, they should be on one attribute.

Upvotes: 1

Related Questions