Virtus::Attribute#value_coerced? not being used

[solnic]

Virtus::Attribute#value_coerced? not being used

[dkubb]

@emmanuel it looks like you added Virtus::Attribute#value_coerced? about a month ago. What's it's purpose? It doesn't look like anything in Virtus is using it.

It's marked as part of the private API, which means nothing outside of Virtus should be relying on it. If something is, then we should probably update it to have @api private in the docs.

Also maybe this is a case where the actual implementation of testing whether a value was properly coerced or not should be pushed off to the coercion libs. Worst case we keep the Virtus::Attribute#value_coerced? method, but just have it delegate all the work to the coercion libs. Best case we can get rid a method that nothing uses.

[solnic]

AFAIR #value_coerced? was added as a convenient method for the case mentioned in the issue.

Regarding custom attributes - I used this example to show that you can implement coercion in the attribute class (kind of like a DM1-style) but the preferred way of handling coercions is to use Virtus::Coercion classes, either extend the existing ones or add new.

The philosophy behind the coercion system is very simple - for every kind of object that may "come in" we have a dedicated Virtus::Coercion class that can handle all sorts of coercions. Every coercion class inherits from Virtus::Coercion::Object which provides default coercion behavior but you are free to override it in your custom classes (that's what most of the built-in classes already do). There's also this trick in Virtus::Coercion::Object that when coercion is not needed then the value will be returned as-is. For example when you call Virtus::Coercion::String.to_string passing in a string object then it will just be returned. This helped us eliminating the need for explicit checks in virtus if the value needs to be coerced or not (the if/else code smell) - it was a pretty cool refactor actually :)

[fgrehm]

hum... so this is the preferred way of doing it then?