RE: Add a hook for color-theme switching

[Drew Adams]

> When I start Emacs, the face ~hl-sexp-face~ is been set
> by the Emacs initialized color-theme.

Vanilla Emacs doesn't use color themes.  It uses custom
themes - the user theme by default.  Color themes are
available through library `color-theme.el'.

Color themes:

https://www.emacswiki.org/emacs/ColorThemes

Custom themes:

https://www.emacswiki.org/emacs/CustomThemes

> Then I use package =circadian= to auto switch color-theme
> or manually switch color-theme with command `disable-theme'
> and `load-theme'. But this face `hl-sexp-face' is defined
> already, usually not good for another switched color-theme.

I don't understand the problem.  Are you saying that when
you switch to another theme (presumably a custom theme)
the appearance of face `hl-sexp-face' changes?

> So I hope there is a hook for switching color-theme like
> `color-theme-switch-hook' etc.

Do you mean that after you switch to another theme you
want to invoke some code?  What code would you invoke?
Is the idea just to make face `hl-sexp-face' have or
keep the appearance you want?