Hi, Tomas Volf <~@wolfsden.cz> skribis:
> However on my first (and second) reading of the documentation I did not > get it, and expected eq? in the below snippet to return #f (since the > pointer being wrapped does equal? to itself). So maybe I am missing > something else as well. > > scheme@(guile-user)> ,use (system foreign) > scheme@(guile-user)> ,use (system foreign-library) > scheme@(guile-user)> (define-wrapped-pointer-type foo foo? wrap-foo > unwrap-foo #t) > scheme@(guile-user)> (define-wrapped-pointer-type bar bar? wrap-bar > unwrap-bar #t) > scheme@(guile-user)> (define open* (foreign-library-function #f "open")) > scheme@(guile-user)> (wrap-foo open*) > $8 = #<foo 7fec7aac1010> > scheme@(guile-user)> (wrap-bar open*) > $9 = #<bar 7fec7d3dd510> > scheme@(guile-user)> (eq? $8 $9) > $10 = #f > scheme@(guile-user)> (equal? open* open*) > $12 = #t <foo> and <bar> are different data types, so no wonder $8 and $9 are not eq?. What this means is that, given a pointer P, (eq? (wrap-foo p) (wrap-foo p)) is always true. HTH! Ludo’.
