Move `WP_Navigation_Block_Renderer` class to its own file.

[swissspidy]

Core requires class definitions to be in their own file.

The WP_Navigation_Block_Renderer class should be moved out of packages/block-library/src/navigation/index.php to its own file, packages/block-library/src/navigation/class-wp-navigation-block-renderer.php

Besides: why is the class not prefixed anyway? I thought Gutenberg fixed class and function prefixes during the build process.

[talldan]

I think it's a long (possibly painful) story why it's implemented this way.

@scruffian might be able to tell you more.

[scruffian]

This is what I did at first but then we moved it back: #57979

See also:
https://core.trac.wordpress.org/ticket/59867#comment:4
#58429

In summary, there are several competing wishes...

On the one hand we want to put code into private functions inside classes so that they can't be used elsewhere in WordPress which would give us a larger surface to maintain with respect to backwards compatibility. Static classes are a good way to achieve this.

On the other hand, at the moment all the PHP rendering code for blocks lives in the block library package, and is back-ported automatically. We are reluctant to start moving block specific code outside of this package.

An ideal solution would allow us to keep all the PHP code inside the block-library package, and also to find a mechanism to keep functions clearly namespaced and not exposed globally for everyone to use. PHP namespaces could be an alternative to a static class.

[swissspidy]

I‘m not suggesting to move this class out of the package, just into a separate file next to index.php. That doesn‘t change anything about the API surface at all.

[scruffian]

I think that would be great but it involves making some changes to the way that the PHP files are built for the block library package. Hopefully someone is able to work on that soon!

[im3dabasia]

I tried working on this issue. What @scruffian said makes sense. The WebPack code for building the code related to blocks is such that the index.php files of the blocks is converted into there respective directory names while building. for example navigation/index.php would become navigation.php in the build. When built the below issue occurs

Originally commented here #57979 (comment)

When built, the class moves to build/block-library/blocks/class-wp-navigation-block-renderer.php
And the "index.php" of the navigation block also moves to the same folder but get renamed to build/block-library/blocks/navigation.php

There's a subtle issue here, if say two different blocks define a utils.php file, one of the blocks's utils.php file is going to override the others. So IMO, we should update our build script to have the following output instead:

build/block-library/blocks/navigation/class-wp-navigation-block-renderer.php
build/block-library/blocks/navigation/index.php

For this change we would need to modify this file tools/release/sync-stable-blocks.js too in WordPress core. So the new paths are correctly fetched by the editor from this file src/wp-includes/blocks/require-dynamic-blocks.php

cc: @swissspidy