https://symfony.com/doc/current/form/create_custom_field_type.html

the first paragraph mentions and finally, how you can register it for use in your application i don't see anything about registering it for use in my application on that page.

usecase:

I'm trying to figure out how to deal with form types in silex which still mentions You can register form types by extending form.types https://silex.symfony.com/doc/2.0/providers/form.html

i guess this is then outdated as well?

I like to keep things inline and not create classes right away (since i'm doing small and quick projects). If i HAVE TO create a class can it be an anonymous one?