A new assertion added into Layout prohibits use of OSS renderers such as provided by Twig. Would like to soften it.

[Saeven]

Feature Request

Q	A
New Feature	no
RFC	no
BC Break	somewhat

Summary

An assertion was added to Layout::getViewModelHelper() which prohibits OSS implementations of RendererInterface in the wild, for example, Twig's TwigRenderer.

protected function getViewModelHelper()
{
    if (! $this->viewModelHelper) {
        /**
         * @psalm-suppress DeprecatedMethod
         */
        $renderer = $this->getView();
        assert($renderer instanceof PhpRenderer); // offending assertion
        $helper = $renderer->plugin('view_model');
        assert($helper instanceof ViewModel);
        $this->viewModelHelper = $helper;
    }

    return $this->viewModelHelper;
}

Adding plugin() to RendererInterface seems a bit heavy handed, but relaxing the assertion to an interface would seem to be more logical, specially since the assertion only serves to protect the contract for ->plugin

Proposal

Would you be open to accepting a PR that either proposes to substitute this assertion for one that looks for an interface that provides plugin() (couldn't find an existing one), or one that adds plugin to RendererInterface (implemented by PhpRenderer)?

[Ocramius]

That code is hacky as hell.

Let's first remove the assertion, but we should really just get rid of such janky consteuct 😬

[Saeven]

Hey Marco, yeah I stopped short of using janky, but it's how it felt!

From a design contract point of view, I can appreciate wanting to protect the implementation - but none of it really fits. Protecting an implementation rather than its contract (non-existent in this case) seemed a bit sketchy.

I'm ready to pitch in - would you like

1. a PR that simply proposes the removal, or
2. a PR that adds plugin to RendererInterface (aggressive, but might be the right target?), and asserts on RendererInterface, or
3. a PR that adds a new PluginInterface, implemented by PhpRenderer, and the assertion is on PluginInterface?

Hope you're doing well!

Cheers. Alex

[Ocramius]

Let's start from the first one 👍