Re: [Vala] How to check if GLib.List is empty?

[Dmitry Golovin <dima golovin in>]

Hello all!

I just tried to compile this:

> int main(string[] argv)
> {
>     List<string> list = new List<string>();
>     assert( list == null );
>     return 0;
> }

It compiles and runs. But this one doesn't compile:

> int main(string[] argv)
> {
>     List<string> list;
>     assert( list == null );
>     return 0;
> }

So, variable should be initialized, even thought it is null after the initialization.

And vala doesn't have so called diamond operator (am I right?), so this code is not valid:

> List<string> list = new List<>();

Would diamond operator be implemented in the future? Anyone needs it?

Regards,
Dmitry

02.12.2014, 17:38, "Luca Bruno" <lethalman88 gmail com>:
> On 02/12/2014 16:34, Виталий Кирсанов wrote:
> >  Hm, indeed. The following piece of code works fine:
> >
> >  int main(string[] argv)
> >  {
> >      List<string> list = new List<string>();
> >      assert( list == null );
> >      return 0;
> >  }
> >
> >  So this seems to be the answer to my question. But still there are two
> >  weird things in my opinion:
> >
> >     - Why I need to call operator new if the result value is still null?
> >     Can't I simply declare a reference List<string> list; and then call e.g.
> >     append()?
>
> Yes, you can. "new List()" is just "null".
> >     - I thought that only references appended with question mark sign (e.g.
> >     List<string>?) can be null, cant' they?
>
> There are several exceptions due to historical reasons. Null is quite
> weak in Vala by default in several places.
> There's an experimental non-null flag for valac, but that's not much
> worked on.
>
> Best regards,
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