We've discussed it, but at this point function call syntax is not
overloadable. Grid.jl <https://github.com/timholy/Grid.jl> overloads the
indexing operator for this purpose instead.


On Tue, Feb 25, 2014 at 5:34 AM, Marek Gagolewski <[email protected]>wrote:

> Dear all,
>
> Is it possible in Julia to define a C++-like operator() for its
> "struct-like" composite types (defined with type....end)? Thanks to such a
> method, one may treat an object as a function.
>
> Here's a GitHub gist illustrating what I'm trying to achieve:
> https://gist.github.com/gagolews/9206364
>
> In other words, I'd like to create a function which has some associated
> (deep copied) objects with it, by calling new_function =
> create_function(data) and such that new_function does not rely on dataanymore 
> (at least from its caller/user perspective). I tried to play with
> Julia's macros, but I'm quite sure it's not the case here.
>
> My inspiration is R's approxfun() which returns a function object that
> interpolates (linearly) a given set of points in 2D. I'm trying to develop
> a similar tool in Julia, but I cannot move on because of this issue.
>
> > (x <- seq(0, 1, length.out=10))
>  [1] 0.0000000 0.1111111 0.2222222 0.3333333 0.4444444 0.5555556 0.6666667
>  [8] 0.7777778 0.8888889 1.0000000
> > (y <- x^2)
>  [1] 0.00000000 0.01234568 0.04938272 0.11111111 0.19753086 0.30864198
>  [7] 0.44444444 0.60493827 0.79012346 1.00000000
> > f <- approxfun(x, y)
> > f(0.35)
> [1] 0.1240741
> > y <- sqrt(x)
> > f(0.35) # no change (y is stored "within" f)
> [1] 0.1240741
> > # more precisely it is a new environment ("hash table")
> > # ASSOCIATED with the function
> > ls(envir=environment(f))
> [1] "f"      "method" "x"      "y"      "yleft"  "yright"
> > f # one source code, but operates on different data
> function (v)
> .approxfun(x, y, v, method, yleft, yright, f)
> <bytecode: 0x2ff5fb8>
> <environment: 0x320a7d0>
>
> Anybody?
>
> Best regards,
> Marek Gagolewski
> http://gagolewski.rexamine.com
>

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