Re: [Vala] How to write float and double values into a binary file?

[Abderrahim Kitouni <a kitouni gmail com>]

Hi all,
                في س، 18-12-2010 عند 14:47 +0100 ، كتب Aleksander Wabik:
> > Phil Housley <undeconstructed gmail com> writes:
> >
> > > Aside: The following doesn't work:
> > >
> > > public void main() {
> > >    float flt = 9.12f;
> > >    var output = FileStream.open("./data.txt","w");
> > >    output.printf("%f", flt);
> > >    float in_flt = 5f;
> > >    var input = FileStream.open("./data.txt", "r");
> > >    int read = input.scanf("%f", out in_flt);
> > >    message("%d %f", read, in_flt);
> > > }
> > >
> > > Because in the generated C, the output file isn't closed before
> > > attempting to read. This is a sort-of-bug, as there is no way to
> > > explicitly close a FileStream...
> >
> > There is a way to close the output file
> >
> >    output = null;
> >
> > as fclose is declared a free_function for FileStream.
>
> This breaks experimental non-null checking; keeping in mind the word
> 'experimental' I may suppose, that some day this will not be
> experimental any more and will become part of language. (BTW. using
> nullable variables is now extremely inconvenient in non-null mode, so
> I'd not advise to make 'output' nullable).
Well, you could also declare output as a pointer and explicitly delete
it (but pointer are also inconvenient, as they need -> instead of .),
but the easiest way (and, I believe, the way it's supposed to be used)
is to put it in a separate block, so it goes out-of-scope as soon as
you're finished with it. e.g.

{
  var output = new FileStream (...);
  // do something with the file
}
// here, as we no longer need the file, it's closed

HTH,
Abderrahim