Hey,
skaller wrote:
> On Tue, 2006-09-26 at 21:47 +1000, Jonathan Kelly wrote:
>
>> Hi,
>>
>> am I right in deducing there are no arrays in felix, despite the
>> temptingly titled sections in the tute and ref man? I mean the sort of
>> arrays a C/C++ programmer would be thinking of, obviously.
>>
>
> Felix has first class fixed length arrays whose length
> is determined by a compile time constant, exactly
> the kind in this C:
>
> #define n 1000
> struct X { int array[n]; }
>
> It also has C style arrays:
>
> module Carray
> {
> requires cstdlib;
> open C_hack;
>
> fun array_alloc[t]: int -> ptr[t] =
> '(?1*)std::malloc(sizeof(?1)*$1)';
> ....
>
>
thanks, that was the opening I needed. I implemented a test using Carray
using the subscript function to access, then thought, I wonder if
there's sugar for that and tried "x.(i)", (which is what I had tried for
the felix array, seeing as the doco said the arrays were really tuples),
but that didn't work, so I tried x[i], nope, then x.[i]. Ta Dah.
Here's what I used to demonstrate the arrays stuff, if you'd like it for
the tute ... hack at will.
//------------
#import <flx.flxh>
open Carray; // needed for array_alloc() and subscript()
open Long; // needed for multiplying longs
val n = 8;
var x = array_alloc[int](7);
var y = array_alloc[long](n);
var z : int ^ 7; // first class felix array
proc s (i:int)
{
if i < 7 do
print i; endl;
subscript[int](x, i) = i * 2;
y.[i] = C_hack::cast[long,int](i) * 3L;
z.[i] = i * 4;
s(i + 1);
done;
}
s(0);
print "dah\n";
print (subscript[int](x, 4)); endl;
print (y.[4]); endl;
print (z.[4]); endl;
//------------
> which are unsafe and can't contain Felix heap pointers.
> You can also use STL vector of course, but again
> only for C++ data types or pointer-free Felix ones.
>
> We're working on a fixed length array whose length
> is determined at construction time dynamically,
> called 'varray' in module Varray.
>
> And possibly also a dynamically extensible array
> like STL vector.
>
> The difficulty here is that there are LOTS of different
> options. Some are hard, for example an extensible
> array which moves its storage around: the way STL handles
> this is very inefficient. Using mmap/realloc is much faster,
> but C++ does not provide a move or 'relocate' method
> for objects: realloc doesn't work with copy ctor.
>
>
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