On Fri, May 20, 2011 at 9:52 AM, Marc Feeley feeley@iro.umontreal.ca wrote:
On 2011-05-20, at 10:40 AM, REPLeffect wrote:
On Mon, May 9, 2011 at 8:55 AM, Marc Feeley feeley@iro.umontreal.ca wrote:
On 2011-05-08, at 4:30 PM, William James wrote:
How do you check to see if a symbol is already bound? To be used in this fashion:
(if (bound? x) (set! x 22) (define x 22))
This is the official way to test is a global variable is bound:
(define (bound? name) (not (##unbound? (##global-var-ref (##make-global-var name)))))
Marc
I tried this running this in the interpreter, and got the following result:
(define (bound? name)
(not (##unbound? (##global-var-ref (##make-global-var name)))))
(bound? mytest)
*** ERROR IN (console)@1779.9 -- Unbound variable: mytest 1>
Am I missing something? 'mytest' was undefined, obviously, but shouldn't bound? have returned #f ?
Try
(bound? 'mytest)
Marc
oh, duh. Now I feel really stupid. :-D