Arc Forumnew | comments | leaders | submitlogin
3 points by tokipin 5979 days ago | link | parent

well, we can closure the methods with the constructor function so they aren't duplicated, at the expense of explicitly requiring the object to be passed to them, or some kind of dispatch mechanism. we can also implement simple inheritance:

  (def inherits (obj1 obj2)
       (fn (key)
           (or (obj1 key) (obj2 key))))
with (apply or ...) we could have a long inheritance chain, but here i have just two objects so the pattern is clear. we can then define objects like so:

  (let _proto (obj
                full (fn (self) (string self!first " " self!last))
                until (fn (self year) (- year self!age)))
  
    (def person (first last age)
           (inherits (obj
                       _proto _proto
                       first first
                       last last
                       age age)
  
                     _proto))
  
  )

  arc> (= p (person "joe" "momma" 18))
  #<procedure>
  arc> (p!full p)
  "joe momma"
  arc> (p!until p 22)
  4
  
  arc> (= q (person "axe" "murderer" 10))
  #<procedure>
  arc> (q!full q)
  "axe murderer"
  arc> (q!until q 22)
  12
because the inheritance is dynamically dispatched or whatitbe, we can alter the methods with the intended effects:

  arc> (q!backwards q)
  Error: "Function call on inappropriate object nil (#<procedure>)"
  arc> (= ((q '_proto) 'backwards) (fn (self) (string self!last " " self!first)))
  #<procedure:gs2439>
  arc> (q!backwards q)
  "murderer axe"
  arc> (p!backwards p)
  "momma joe"

  arc> (= ((q '_proto) 'until) (fn (self age) "a long time"))
  #<procedure:gs2451>
  arc> (q!until q 22)
  "a long time"
  arc> (p!until p 18)
  "a long time"
note the 'inherits' function is agnostic. we can inherit from arbitrary objects and functions or what have you, just that in this case it was used to inherit from a hidden prototype

anarki supposedly has user definable syntatic sugaries, so the (q!blah q) pattern could be sugarized



2 points by almkglor 5979 days ago | link

http://arclanguage.org/item?id=7365

-----