Re: [Vala] Static array initialization

["Cayle Graumann" <cayle graumann gmail com>]

Jurg,


On 3/8/07, Jürg Billeter <j bitron ch> wrote:
> On Don, 2007-03-08 at 17:48 -0600, Cayle Graumann wrote:
> > Speaking of array initialization - I came across an oddity the other
> > day in version 0.0.6 in that the following syntax would not compile.
> > I have not tried it with 0.0.7 yet as I am still trying to change over
> > my code to the new constructor syntax to test other things yet.
> >
> > function x (int buffersize) {
> >
> >       int[] i;
> >       if(buffersize>10) {
> >              i = new int[100];
> >       } else {
> >              i = new int[10];
> >       }
> >
> > }
> >
> > The vala compiler complained about the "int[] i" not being valid.
>
> That's a known bug in the parser, we have to refactor it a bit to get
> that working. We'll hopefully fix that for 0.0.8.
>
> > I like the fact that we can now resize arrays, but wonder at how
> > efficient an implementation it is.  I have some code I'm porting that
> > extensively uses a linked list (C# ArrayList) of integer arrays to
> > allow efficient array growth, and if the new resizable arrays are good
> > enough then I might not worry about reworking that code.
>
> It uses g_renew which just calls realloc, that should be pretty fast in
> general but it probably wouldn't be that efficient to resize an array
> one by one all the time. The C# ArrayList is not a linked list, AFAICT,
> but an array that gets resized in steps of different sizes, which is
> fast enough for many use cases.
>
> I'm in fact currently implementing a generic ArrayList class for Vala
> that does exactly that. I've to fix some bugs in the compiler first to
> get this nicely integrated, though. If you're interested in that
> library, I'll cc you when I have some experimental version ready.
>
> Jürg

I wasn't thinking of resizing every time one by one, but in fairly
sizeable chunks of 512 or 1024 int - so using resize may actually work
for me.  I'll just have to see.  I'd like to see your ArrayList
implentation when you done.  If your wondering what I'm working on - I
am reimplementing the speedy non-SAX XML parser Vtd-Xml from
ximpleware.  There is a java and a C# implementation.  They also have
a C version, however it uses an exception library based on
preprocessor macros.  The Vala implementation will use signals rather
than exceptions.


Cayle in Missouri