[Vala] How to pass items of an array as out parameters?

[Sandino Flores Moreno <tigrux gmail com>]

In my program, I need to initialize variables that are items of an array.
It's a situation that can be roughly simplified to this:

[test.vala]

void modify(out int n) {
        n = 5;
}

void main() {
        int[] a = new int[3];
        for(int i=0; i<a.length; i++)
                modify(out a[i]);
}

[/test.vala]

However, I get this error:

$ valac test.vala
test.vala:8.10-8.17: error: ref and out method arguments can only be
used with fields, parameters, and local variables
                modify(out a[i]);



More specifically, I had this code that is valid in C:

    OMX_BUFFERHEADERTYPE *inBufferAudioDec[2];
    for(i=0; i<2; i++) {
        err = OMX_AllocateBuffer(audiodechandle, &inBufferAudioDec[i],
0, NULL, buffer_in_size);
        if (err != OMX_ErrorNone)
            exit(1);
    }

That is translated to Vala as shown:

    Omx.BufferHeader[] inBufferAudioDec = new Omx.BufferHeader[2];
    for(i=0; i<2; i++) {
        err = audiodechandle.allocate_buffer(out inBufferAudioDec[i],
0, null, buffer_in_size);
        if (err != Omx.Error.None)
            Posix.exit(1);
    }

But, Vala fails with the error specified in the canonical example.

So, how should I pass items of an array as out parameters of a method
or function?