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24.1.2.2 Examples of Feature Expressions

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