What is the reason to rename --mdc-* to --md-*

[scherler]

Doing the update of our development from mwc to md would save quite some time if I did not have to rename all our CSS variables, which leads me to the question of why the decision was taken to rename the CSS variable. I do understand the tags but the variables could have been the same.

[asyncliz]

The variable names would be completely different due to the naming schema that was designed for Material 3 tokens.

Since none of them would be compatible, we used a different prefix to signify the breaking change.

A smoother upgrade from <mwc-*> to <md-*> is on our radar though. We have many folks at Google with the same problem! I'm hoping to have it as a goal for 2024.

[scherler]

Thank you very much for your response and yes makes sense with the variables. Regarding the update route, some of the new components do not support fundamental methods e.g. md-menu does not support @action anymore, it may be a good idea to drop a line in the docu on how to migrate your <mwc-menu @action ... code, I am using the menu as an example since I am currently working on it 😉 but I would await this on any component.

[asyncliz]

I would love to have good documentation for migration support!

The tl;dr of our plan is to create something like @material/web/migrations/m2/mwc-button that would call <md-*> implementations under the hood, style itself to look like M2, and try to map as many 1:1 APIs like methods, events, and custom properties.

Later on, the same concept can be used for breaking changes that require migrations, such as a re-design of a component. Slider's on the chopping block for a re-design soon for example.

There are very few engineers on MWC at the moment though, so if this sounds like a fun project to explore we'd welcome contributions! You can also chat with us on lit.dev/discord in the #material channel :)