fix(theme): deep merge configs

[curbengh]

What does it do?

Fixes #3964

How to test

cc @cmpute

# themes/xxx/_config.yml
a:
  c: 2

# _config.yml
theme_config:
  a:
    b: 3

package.json
-  "hexo": "^4.1.1",
+  "hexo": "curbengh/hexo#deepmerge_theme_config"

2. rm package-lock.json && rm -rf node_modules/
3. npm install
4. hexo clean && hexo server (or hexo generate if relevant)
5. Verify theme.a should have { b: 3, c: 2}

Maintainers:

git clone -b deepmerge_theme_config https://github.com/curbengh/hexo.git
cd hexo
npm install
npm test

Pull request tasks

• Add test cases for the changes.
• Passed the CI test.

[coveralls]

Coverage decreased (-0.006%) to 97.133% when pulling 9b401fd on curbengh:deepmerge_theme_config into 2c50d3b on hexojs:master.

[cmpute]

Thanks!

[SukkaW]

LGTM!

[curbengh]

Verified in a test blog.

[Teekivi]

Is it possible to (selectively) opt out of deep merging theme configs? I am using a theme called Hermes which uses a dictionary for its menu. It has some menu items predefined. I want to replace all of those with my items. Due to deep merging, I end up with a menu that contains both the predefined and my items.

[curbengh]

would modifying the theme's config.yml (instead of theme_config) resolve the issue? or remove the default value.

[Teekivi]

Yes, modifying the theme's config.yml would indeed resolve issue. But having to modify the theme's source code kind of defeats the purpose of theme_config. As the documentation puts it:

Instead of forking a theme, and maintaining a custom branch with your settings, you can configure it from your site’s primary configuration file.

Enforcing deep merge of configs without making it opt-in or opt-out makes using theme_config cumbersome or in some cases impossible with (I believe) quite a lot of pre-existing themes.

I imagine that lots of themes come with example menus etc to showcase them out-of-the-box. If a menu is defined using a dictionary and the user happens to want to use exactly the same menu item names and in that same order as the predefined one, the user is in luck. In other cases, they'll want to omit and/or reorder predefined items, both of which are currently impossible via theme_config due to deep merge.

[yezige]

awesome