Re: [Vala] GBinding support?

Am 21.06.2010 09:29, Fredderic Unpenstein wrote:
On 21 June 2010 01:57, Frederik <scumm_fredo gmx net> wrote:
GLib/GObject 2.26 will add property binding [1]. The straightforward way to
support this in Vala would be:
 Object.bind_property (foo, "x", bar, "y");
 Object.bind_property (foo, "x", bar, "y", BindingFlags.BIDIRECTIONAL);

Would foo.x.bind_property be a possibility?  And perhaps
bind_bidirectional or bind_with (do you bind anything else, other than
properties, on an object property?)...  Maybe then also bind_property
could become bind_to or something equaly less redundant?

A problem is that 'foo.x' will evaluate to the value of the property,
not representing the property itself. So, if you write

  foo.x.bind_property (bar.y);

and if 'foo.x' is 4 and 'bar.y' is 5 it would essentially mean

  4.bind_property (5);

Personaly, I like the operators, but they're a little limited once you
add extra varients or options, as with the connect family.  Unless
some syntax is added for general operator functions...  eg:

   foo.x +> [BIDIRECTIONAL] bar.y;

which could also make += signal connection useful again.  Perhaps
adding support for a bracketed comma-separated list with the extra
arguments, instead.

Personally, I prefer descriptive names over symbolic operators. The question
is whether the property binding feature is essential enough to justify extra
syntax (keyword, operator) just to be type safe.

And how to deal with 'g_object_bind_property_full'? It takes two TransformFuncs
but only one user_data/GDestroyNotify pair.
 (foo.x, celsius_to_fahrenheit) <+> (bar.y, fahrenheit_to_celsius);
 (foo.x, (b, s, t) => { }) <+> (bar.y, (b, s, t) => { });

That's sort of what I was saying with bracketing above, too.  A
general syntax pattern like that might help with other places where
syntactic support would be useful but presently shunned.


Best regards,


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