Re: [Vala] out, ref and GError parameters.

[Jürg Billeter <j bitron ch>]

On Don, 2007-03-15 at 14:57 -0300, Alexandre Moreira wrote:
> On 3/15/07, Juerg Billeter <j bitron ch> wrote:
> > As mentioned before, you can already start implementing by using the
> out
> > syntax, you just will have to port the code someday but that shouldn't be
> > difficult.
>
> I can't see how use the GError stuff with out syntax. Unless I
> generate a lot of Error variables to use with my code, I can't simply
> pass on the error handle the user gave me to the functions I call,
> because the user might have passed it as null, and whenever I try to
> pass this to the next function, it will dereference it :(
>
> I can't check for null, and I can't use it in any way without
> dereferencing it...

It should work as follows:

Method definition
        public void test (out Error error) {...}

Checking for null
        if (out error != null) {...}

Passing to next function
        foo (out error);

In short, as long as you use `out error` instead of just `error`, it
shouldn't get dereferenced. I haven't used this workaround for real
error handling, though, so I might have overlooked something. Please
report if there are still problems with that scheme.

Jürg