On 3/25/2010 10:30 AM, Igor Stasenko wrote:
> Then i really wonder, why people find an Alien so attractive?

There are two different reasons, one is philosophical, one is practical. 
The practical issue is callbacks. When you need them you just need them :-)

The philosophical point is about how a system like Squeak should 
integrate into the external environment. My opinion is that the VM 
should provide a safe cross-platform abstraction layer. As a 
consequence, I am in favor of plugins that provide abstractions, have a 
well-defined interface, and are safe however you use them. The only real 
sin I've ever committed in this regard was OpenGL because the interface 
is so big and the handling of extensions tricky otherwise.

Gilad's opinion (and I hope I'm not misrepresenting him here since this 
an extrapolation from discussions with Eliot) as far as I understand it 
is that the VM should be basically invisible - just the execution 
machinery and for the rest you go straight to the OS and do everything 
there.

That's a perfectly valid position, and Alien makes that point quite 
explicitly with moving even the marshalling into the image. I.e., what 
Alien really provides is just an absolutely minimalistic thunk for 
callout and callback; everything else is up to you. I can appreciate 
that approach; it's just not my view on how a system like Squeak should 
function.

I think what excites people who understand this is the philosophical 
difference. Having access to everything at your fingertips is powerful, 
no doubt about it.

Plus, most people have no clue what they're talking about when it comes 
to plugins vs. FFI vs. Alien and just repeat what someone else said. 
Sad, but true.

Cheers,
   - Andreas