[RFC]: Make AbstractHelper internal and Guarantee a renderer for existing implementors

[gsteel]

RFC

Q	A
Proposed Version(s)	3.0.0
BC Break?	Yes

Goal

To further improve SA and minimise the number of checks for "Do I have a renderer yet", either make the renderer a constructor dependency for HelperPluginManager (And provide a factory) or throw an exception on retrieval if null, effectively making the signature for HelperPluginManager::getRenderer(): RendererInterface and the signature for AbstractHelper::getView(): RendererInterface (i.e. enforce a return type) … It would also be a good idea to update the signature for HelperInterface::getView()!

Background

This was recently surfaced in slack because until recently, the documented return type for AbstractHelper::getView() was changed from RendererInterface to RendererInterface|null (The latter being what it actually is). Consumers extending AbstractHelper now have errors in their SA tools.

Guaranteeing a renderer for both of these will likely solve a large number of possible type errors and make the public api of the package easier to work with.

Considerations

There will be a number of laminas packages affected by this change that will require work to upgrade to 3 - at least i18n, flash-messenger, form and likely more.

The signature changes will potentially affect any consumer that has extended AbstractHelper - the impact is unlikely to cause to many problems unless they have re-implemented the getView() method which is unlikely

Proposal(s)

• Change the docs for "Advanced Helper Usage" so that the examples of creating and registering helpers do not extend AbstractHelper providing examples of a simple invokable as well as a helper having constructor dependencies along with an example factory with instructions on registering plugins.
• Change the return types for methods retrieving the underlying view renderer and make them exceptional
• Update all callers of these methods, fix broken tests and introduce new tests to cover the changed behaviour
• Mark AbstractHelper as @\internal to discourage extending it outside of the package