Re: Why shouldn't we have a #if .... #else .... #endif construct in Emacs Lisp?

[Stefan Monnier via "Emacs development discussions." <emacs-devel@gnu.org>]

> --8<---------------cut here---------------start------------->8---
> (defmacro cif (test then &rest else)
>   "Evaluate TEST during macro-expansion and return THEN or ELSE."
>   (if (eval test t) then else))
> --8<---------------cut here---------------end--------------->8---

FWIW I've used such macros in packages under the name
`<PKG>--if-when-compile`.

Also, FWIW, I've used the following variant to let the
compile-time check be reconsidered at runtime:

    (defmacro TeX--if-macro-fboundp (name then &rest else)
      "..."
      (declare (indent 2) (debug (symbolp form &rest form)))
      (if (fboundp name)             ;If macro exists at compile-time, just use it.
          then
        `(if (fboundp ',name)               ;Else, check if it exists at run-time.
             (eval ',then)                  ;If it does, then run the then code.
           ,@else)))


-- Stefan