makes $layerResolver protected in Category view

[BlackIkeEagle]

When you need to overwrite this View controller but want to inherit
since most of the functionality is exactly the same you have access to
everything but the $layerResolver which is kind of annoying. Its also
pointless to need to copy the constructor to your child class just
because of this. So make $layerResolver protected.

Signed-off-by: BlackEagle ike.devolder@gmail.com

[orlangur]

you have access to everything but the $layerResolver which is kind of annoying

Protected properties are just a bad smelling legacy.

It's also pointless to need to copy the constructor to your child class just because of this

It is the lesser evil. Takes some 0.5s in modern IDEs.

See #8420 (comment) for details.

[maghamed]

@BlackIkeEagle Magento discourages usage of Inheritance as a mean for extension/customization of entities.
So, ideally there shouldn't be inheritance at all among the Magento entities. And all existing examples of inheritable you can see in our codebase could be considered as Technical Debt.
Thus, if there is no Inheritance -> you no need the protected property.

What you can do in this specific case:

if you need to overwrite/extend layer object being instantiated
$this->layerResolver->create(Resolver::CATALOG_LAYER_CATEGORY);
you could provide own version of Magento\Catalog\Model\Layer\Resolver object trough DI into \Magento\Catalog\Controller\Category\View

current implementation of \Magento\Catalog\Controller\Category\View couldn't be considered as a good example of Controller's code, because there is some logic which doesn't belong to controller (initCategory).

But nevertheless, I believe that you could just manipulate with external dependencies which are injected using DI, and substitute them if needed on own versions.
If you need several entities (read versions) of \Magento\Catalog\Controller\Category\View but configured differently - you could achieve this creating VirtualType(-s) based on \Magento\Catalog\Controller\Category\View.

[BlackIkeEagle]

The change was made so we don't have to copy all code from the current Category View controller to our overriding controller. But we could do it with DI and have some duplication.