[blog] Bringing consistency to Material UI customization APIs

docs/data/material/migration/migrating-from-deprecated-apis/migrating-from-deprecated-apis.md

@@ -26,6 +26,20 @@ If you need to run a specific codemod, those are also linked below.
 
 :::
 
+## Package-wide deprecated APIs
+
+### Inner element overrides
+
+The `slots` and `slotProps` APIs are in the process of being standardized.
+The analogous APIs—`components`, `componentsProps`, `<SlotName>Component`, and `<SlotName>Props`—are going to be deprecated and eventually removed.
+This improves the developer experience through consistency, predictability, and reduced cognitive load.
+
+### Composed CSS classes
+
+The composed CSS classes are going to be deprecated and eventually removed in favor of atomic class alternatives.
+For example, the `.MuiAccordionSummary-contentGutters` class was deprecated in favor of the `.MuiAccordionSummary-gutters` and `.MuiAccordionSummary-content` classes.
+This improves the developer experience by reducing bloat and cognitive load.
+
 ## Accordion
 
 Use the [codemod](https://github.com/mui/material-ui/tree/HEAD/packages/mui-codemod#accordion-props) below to migrate the code as described in the following sections:

docs/pages/blog/bringing-consistency-to-material-ui-customization-apis.js

@@ -0,0 +1,7 @@
+import * as React from 'react';
+import TopLayoutBlog from 'docs/src/modules/components/TopLayoutBlog';
+import { docs } from './bringing-consistency-to-material-ui-customization-apis.md?muiMarkdown';
+
+export default function Page() {
+  return <TopLayoutBlog docs={docs} />;
+}

docs/pages/blog/bringing-consistency-to-material-ui-customization-apis.md

@@ -0,0 +1,70 @@
+---
+title: Bringing consistency to Material UI customization APIs
+description: We're standardizing two key areas of the Material UI customization APIs to reduce complexity and cognitive overhead. Read on to learn what's changing.
+date: 2024-03-11T00:00:00.000Z
+authors: ['diegoandai']
+tags: ['Material UI', 'Product']
+card: true
+---
+
+The MUI Core team is working on two initiatives to standardize the Material UI API: The first applies to overriding inner elements, and the second applies to component CSS classes.
+In both cases, the purpose is to provide a more consistent developer experience for the community.
+
+Let's explore how these changes are taking shape:
+
+## Inner element overrides
+
+Because Material UI components often contain multiple DOM nodes, it's common to need to modify the structure, behavior, and style of inner elements.
+For example, you might want to modify the Slider's thumb element to grow in size when dragged:
+
+<iframe src="https://codesandbox.io/embed/nw34ry?view=Editor+%2B+Preview&module=%2Fsrc%2FDemo.tsx&hidenavigation=1"
+     style="width:100%; height: 200px; border:0; border-radius: 4px; overflow:hidden;"
+     title="blog/material-ui-early-2024-standardization/slider-slots-example"
+     allow="accelerometer; ambient-light-sensor; camera; encrypted-media; geolocation; gyroscope; hid; microphone; midi; payment; usb; vr; xr-spatial-tracking"
+     sandbox="allow-forms allow-modals allow-popups allow-presentation allow-same-origin allow-scripts"
+   ></iframe>
+
+You can achieve this by providing custom components through the `slots` prop.
+The demo above provides a custom thumb component that uses the Slider's internal `dragging` and `focusedThumbIndex` states to change its appearance.
+[Open the CodeSandbox](https://codesandbox.io/p/sandbox/blog-material-ui-early-2024-deprecations-slider-slots-example-nw34ry?file=%2Fsrc%2FDemo.tsx) to see the implementation.
+
+The problem is that this slot pattern exposed through the `slots` prop is not consistent across the library.
+Some components implement the `slots` prop, but others have a `components` prop, which works almost exactly as the `slots` prop.
+Other components have props named `<SlotName>Component` for more specific use cases—for example, the Accordion features a `TransitionComponent` prop for implementing custom transitions.
+
+The same inconsistencies are found with the `slotProps` prop, which is used to provide custom props to inner elements.
+Some components have the `slotsProps` prop; others have a `componentsProps` prop; and still others have props named `<SlotName>Props`.
+
+This lack of consistency leads to unnecessary complexity for both developers and maintainers.
+To resolve this, the `slots` and `slotProps` API will be standardized across all components, and the analogous APIs will be deprecated and eventually removed.
+
+## Component CSS classes
+
+The most common way to customize a component's look and feel is to target its CSS classes.
+For example, you might want to customize a Chip's primary color and set it to a different color when it's clickable:
+
+<iframe src="https://codesandbox.io/embed/d7xqr6?view=Editor+%2B+Preview&module=%2Fsrc%2FDemo.tsx&hidenavigation=1"
+     style="width:100%; height: 200px; border:0; border-radius: 4px; overflow:hidden;"
+     title="blog/material-ui-early-2024-standardization/chip-classes-example"
+     allow="accelerometer; ambient-light-sensor; camera; encrypted-media; geolocation; gyroscope; hid; microphone; midi; payment; usb; vr; xr-spatial-tracking"
+     sandbox="allow-forms allow-modals allow-popups allow-presentation allow-same-origin allow-scripts"
+   ></iframe>
+
+You can do this by targeting `chipClasses.colorPrimary` and `chipClasses.clickable`, respectively.
+The demo above targets `.MuiChip-colorPrimary` and `.MuiChip-clickable.MuiChip-colorPrimary` to achieve this result.
+[Open the CodeSandbox](https://codesandbox.io/p/sandbox/blog-material-ui-early-2024-deprecations-chip-classes-example-d7xqr6?file=%2Fsrc%2FDemo.tsx) to see the implementation.
+
+The problem is that you could also use the `chipClasses.clickableColorPrimary` composed class, which composes the atomic clickable and color classes.
+These composed classes bloat the API without adding significant improvements.
+For example, this pattern adds 26 CSS classes to the `Chip` component.
+
+The composed classes also reduce the predictability of the CSS classes API, as the compose order and which props get composed are arbitrary decisions.
+This adds unnecessary cognitive overhead for developers as well as significant complexity for maintainers.
+Because of these issues, composed CSS classes will be deprecated and eventually removed in favor of atomic class alternatives.
+
+## Standardization process
+
+This initiative aims to improve the developer experience for the Material UI community.
+To provide the smoothest migration from these APIs, they will be deprecated first and removed at a future date, likely the end of 2024.
+With each deprecation, we'll update the [migration guide](https://mui.com/material-ui/migration/migrating-from-deprecated-apis/) and provide [codemods](https://github.com/mui/material-ui/tree/master/packages/mui-codemod#deprecations) to simplify the process.
+As always, please [open a GitHub issue](https://github.com/mui/material-ui/issues/new/choose) if you encounter any unexpected behavior with the standardized APIs.

docs/src/modules/components/TopLayoutBlog.js

@@ -111,6 +111,11 @@ export const authors = {
     avatar: 'https://avatars.githubusercontent.com/u/805073',
     github: 'colmtuite',
   },
+  diegoandai: {
+    name: 'Diego Andai',
+    avatar: 'https://avatars.githubusercontent.com/u/16889233',
+    github: 'DiegoAndai',
+  },
 };
 
 const classes = {