hitesh wrote:
> I'm working on some opengl code in clojure and I want to specify a
> vertex. However, instead of passing in the three arguments it wants,
> I want to specify a single vector of 3 elements. How can I do this?
>
> Here's what it would normally look like (gl represents the current
> opengl drawing context object):
>
> (.glVertex3f gl 1.0 3.7 0.0)
>
>
> Here's what I want to write:
>
> (let [ point [1.0 3.7 0.0] ]
> (.glVertex3f gl point))
>
>
> I've tried playing around with apply.
>
> (apply .glVertex3f gl point)
>
> But it generates an error: no matching method glVertex3f for class
> com.sun.opengl.impl.GLImpl.
>
> I'm not sure what this concept is called, but here's some code in
> other languages that demonstrates it.
>
> Here's the equivalent concept in Haskell
>
> foo :: (Show a) => a -> a -> IO ()
> foo a b = mapM_ print [a, b]
>
> *Main> uncurry foo (1,2)
> 1
> 2
>
>
> Or in Ruby
>
> def foo(a,b)
> puts a
> puts b
> end
>
> x = [1,2]
>
> foo *x
> 1
> 2
>
>
> Any ideas?
>
> Thanks,
> Hitesh
>
Ok, maybe I just ran into a nicer answer to your problem. There is a
macro called memfn that is used to turn java functions into first class
functions. Here is an example with strings, which are just standard
java string objects so it should be the same:
user=> (def index-of (memfn indexOf substr))
#'user/index-of
user=> (def mystr "foobar")
#'user/mystr
user=> (apply index-of [mystr "ba"])
3
Where the "foobar" string is the instance that is getting the indexOf
called, like this in java:
mystr.indexOf("ba")
This could be another way to do what you are trying to do.
-Jeff
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