:preface
is evaluated firstThe :preface
section is evaluated before anything else, except
:disabled
and :ensure
. It can be used to establish
function and variable definitions that will:
:if
test.
Note that whatever is specified within :preface
is evaluated
both at load time and at byte-compilation time, in order to ensure
that definitions are seen by both the Lisp evaluator and the
byte-compiler. Therefore, you should avoid having any side-effects in
your :preface
forms, and restrict them to symbol declarations
and definitions.