cl-block Vs let form in elisp

Question

when to use cl-block over the most common let scoping?

When a form is expected to return multiple possible values, is cl-block the choice over let?

Answer 1

I believe that it's best to avoid cl-block. There are only 23 uses of cl-block in the whole Emacs core. I've been writing Emacs packages for some time and I couldn't tell at the spot what cl-block does. A list of values is usually better, or eieio if you want complex things.

Answer 2

cl-block isn't designed for the same purpose as let. Its purpose is to be used in macros to work with control flow in the way which resembles Common Lisp. One would use cl-block to implement functionality of return-from or a pattern-matching device with guards etc. It's not expected that non-library code would use this macro.