after two months of active development, the Vala programming language has reached version 0.13.0.
Changes
- More refactoring in the code generator.
- Improvements to the .gir reader.
- Switch JSON-GLib bindings to .gir.
- Drop deprecated support for D-Bus GLib in favor of GDBus.
- Many bug fixes and binding updates.
Some numbers: 314 commits and 94 bug fixes since version 0.12.0. So this new development release is a mix of enhancements and fixes.
A noteworthy change is the deprecation of copying delegates. A delegate is copied when it is assigned to an owned delegate variable like this:
SourceFunc a = () => false;
SourceFunc b = a;
You will get a warning: "copying delegates is discouraged" or "copying delegates it not supported". This is because of the nature of delegates in glib. Owned delegate variables have a related target and a GDestroyNotify, but it's not known how to copy/ref the target. Therefore, it's impossible to copy/ref a delegate target.
So, how do we shut the warning? There are two ways:
1) If you don't need owned delegate, you can assign to an unowned variable like this: unowned SourceFunc b = a;
2) If you want to transfer the ownership: SourceFunc b = (owned) a; After this, you can still invoke a() but the target will not be destroyed anymore when a runs out of the scope.
You might experience the same warning for delegate properties as well, like this:
public SourceFunc func { get; set; }
Here there are two solutions:
1) If you need owned delegate, use owned set like this: public SourceFunc func { get; owned set; }, while keeping the getter unowned.
2) If you don't need owned delegate: public unowned SourceFunc func { get; set }
It must be noted that due to a bug (now fixed in this release), although you defined an owned delegate property, it was practically unowned.
