Richard Shann <richard.sh...@virgin.net> skribis:
> (if (defined? 'define-once)
> (define-once ToggleTripleting::InsideTriplet #t)
> (eval-string "(if (not (defined? 'ToggleTripleting::InsideTriplet))
> (define ToggleTripleting::InsideTriplet #t))"))
Rather something along these lines:
(cond-expand ((not guile-2)
(define-macro (define-once var expr)
`(if (not (defined? ',var))
(define ,var ,expr))))
(guile-2 #t))
This will do nothing on Guile 2.0, and will define ‘define-once’ on 1.8.
HTH,
Ludo’.
