When a form type provides a BC layer with old form names (all core types
do), the form registry will ask for type extensions registered on the
legacy name for BC, and trigger a warning if it finds any.
The DependencyInjectionExtension should not trigger warnings on its own
when being asked for such extensions (especially when it has none
registered).
Core extensions are also registered using the proper extended type
rather than legacy names.
With implementations of this interface, existing types can be amended.
The Csrf extension, for example, now contains a class FormTypeCsrfExtension
that adds CSRF capabilities to the "form" type.
To register new type extensions in the DIC, tag them with "form.type_extension"
and the name of the extended type as alias.
The extension classes are now the only constructor argument of the FormFactory class. They replace the existing "type loader" classes.
new FormFactory(array(
new CoreExtension($validator, $storage),
new CsrfExtension($csrfProvider),
new DoctrineOrmExtension($em),
));
Together with a few upcoming commits this mechanism will make
* extension of the form framework in bundles and
* usage of the forms outside of Symfony2
much easier.
