redirecting functions

[cormullion]

Ahoy there!

What's the best way to do this:

Code: Select all

(define (task)
   (action))

(if (= x 3)
  (set 'action '(sin x))
  (set 'action '(pow x 5)))

(set 'x 4)

(task)

Ie you want the 'action' function to do different things when it's called.

[Jeff]

Code: Select all

(if (= x 3) 
  (set 'action '(sin x)) 
  (set 'action '(pow x 5)))

(eval (expand action 'x))

[cormullion]

Thanks Jeff. Eventually I decided to do it using "fn".

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 (set 'do-content (fn (f) (single-entry-by-id (CGI:get {entry-id}))

this doesn't evaluate till I want to call it. There's probably a better way, but this works for now... :-)

[jrh]

God, what a mongrelized bastard newLISP is! (this is a good thing.)

With C library support and sockets, a TCL/TK interface, and now Java graphics it's the language of The Day of the Triffids. Watch out, you will be assimilated!

[cormullion]

God, what a mongrelized bastard newLISP is! (this is a good thing.)

With C library support and sockets, a TCL/TK interface, and now Java graphics it's the language of The Day of the Triffids. Watch out, you will be assimilated!

That's one way of putting it! :-) Or you could say that newLISP is a good citiizen and a considerate neighbor. Not so dramatic, though..!

[Jeff]

You could do it without the eval if you want it to not evaluate yet:

Code: Select all

(if (= x 3) 
  (set 'action '(sin x)) 
  (set 'action '(pow x 5))) 

(setq to-be-evaled-later (expand action 'x))