Is it possible to determine if an annotation value is presen

Question

Is it possible to determine if an annotation value is present because it was the default or if it was set manually

Grégory Lureau · Answer

How is it possible to set an annotation by default What does that mean

Jiaxiang · Answer

I think it means when you define an annotation class you can specify a default value for the annotation value arguments

jameskleeh · Answer

Correct

jameskleeh · Answer

In Micronaut we support the notion of an argument that is actually set vs a default value

jameskleeh · Answer

I ve determined the likely way to determine this is through the constructor of the annotation however I don t know how to get the default values from the parameters Any ideas < Jiaxiang>

Jiaxiang · Answer

I can think of it but what is the usage of that I feel like you have all you need with getting the value itself it shouldn t matter whether it comes from a default value or defined in the code

jameskleeh · Answer

its more efficient to store the default values from annotations once instead of each time they are used

jameskleeh · Answer

so its split out that way to reduce memory usage

jameskleeh · Answer

Micronaut stores annotation data in our own API that is accessible at runtime so no runtime reflection is necessary to retrieve that info

Jiaxiang · Answer

to store it I will need a flag in KSP to determine if a value is present in code or alternatively do a computation every time user query it either sacrifices space or time efficiency in my opinion

Jiaxiang · Answer

also we don t actually do runtime reflection to get the annotation value if reflection is your concern

jameskleeh · Answer

reflection is a concern for us at runtime not compile time

jameskleeh · Answer

So are you saying that it isn t possible with the current version of KSP

Jiaxiang · Answer

it isn t possible in current version I can see it is doable but need more context on the necessity of this use case

jameskleeh · Answer

A boolean on KSValueArgument `isDefaultValue` or something of the sort would be sufficient I believe

jameskleeh · Answer

perhaps not actually

Jiaxiang · Answer

I would call it `isPresent` since user can still write a value equal to default value and I think you are more interested in if user has written the value or not rather than the actual value

jameskleeh · Answer

I ll create an issue

jameskleeh · Answer