For example, suppose that
in implementation A, the features spice and perq are present,
but the feature lispm is not present;
in implementation B, the feature lispm is present,
but the features spice and perq are
not present;
and
in implementation C, none of the features spice, lispm, or perq are
present.
Figure 24–1 shows some sample expressions, and how they would be
read_2 in these implementations.
(cons #+spice "Spice" #-spice "Lispm" x)in implementation A ...(CONS "Spice" X)in implementation B ...(CONS "Lispm" X)in implementation C ...(CONS "Lispm" X)(cons #+spice "Spice" #+LispM "Lispm" x)in implementation A ...(CONS "Spice" X)in implementation B ...(CONS "Lispm" X)in implementation C ...(CONS X)(setq a '(1 2 #+perq 43 #+(not perq) 27))in implementation A ...(SETQ A '(1 2 43))in implementation B ...(SETQ A '(1 2 27))in implementation C ...(SETQ A '(1 2 27))(let ((a 3) #+(or spice lispm) (b 3)) (foo a))in implementation A ...(LET ((A 3) (B 3)) (FOO A))in implementation B ...(LET ((A 3) (B 3)) (FOO A))in implementation C ...(LET ((A 3)) (FOO A))(cons #+Lispm "#+Spice" #+Spice "foo" #-(or Lispm Spice) 7 x)in implementation A ...(CONS "foo" X)in implementation B ...(CONS "#+Spice" X)in implementation C ...(CONS 7 X)Figure 24–1: Features examples