Does Vala support self-invoking?

问题

Is there any way that Vala supports Self Invoking? Either with a class, or with a method?

Javascript supports self invoking like below. Which is what im looking for.

   (function(){
   // some code…
   })();

I'm attempting to load a class into a hashmap for dynamically loading.

回答1:

using Gee;

[CCode (has_target = false)]
delegate void MyDelegate();

int main() {
        var map = new HashMap<string, MyDelegate>();

        map["one"] = () => { stdout.printf("1\n"); };
        map["two"] = () => { stdout.printf("2\n"); };

        MyDelegate d = map["two"];
        d();
        return 0;
}

If you need a target in your delegate you have to write a wrapper, see this question: Gee HashMap containing methods as values

As you can see, you don't need self invokation. Self invokation would look something like this:

int main() {
        (() => { stdout.printf("Hello world!\n"); })();
        return 0;
}

This is not supported by Vala (I tested this with valac-0.22).

Invoking a delegate var works as expected:

delegate void MyDelegate();

int main() {
        MyDelegate d = () => { stdout.printf("Hello world!\n"); };
        d();
        return 0;
}

来源：https://stackoverflow.com/questions/19495057/does-vala-support-self-invoking