On 6-Oct-06, at 4:25 PM, <bryce at kampjes.demon.co.uk> wrote:

> Andreas Raab writes:
>> J J wrote:
>>>> No. First, Exupery is not a JIT.
>>>
>>> I had been told it was.  In this list actually.
>>
>> Yeah, it's quite confusing actually. I found the statement that
>> "[Exupery is] a "JIT" for Squeak that doesn't compile just in time"
>> which (to me) makes no sense as "JIT" stands for "just in time" so  
>> how
>> could a JIT not compile just in time? ;-)
>
> When Exupery is running in a background thread a user shouldn't
> notice that it's not a "real" JIT. So calling it a JIT is fair.

Actually I don't think JIT is a sensible description at all; it isn't  
accurate and it doesn't really indicate the advantages that Exupery  
could have. For example, no extra startup costs, easier extension/ 
maintenance/optimising because it is written in a sensible language,  
access to all of the reflexive capabilities of the system, trivial  
fallback  if the system is run on an unsupported platform  (it just  
doesn't do the compiles and leaves everything to the interpreter),  
potential for using a spoon-like inter-image communication system to  
allow the compiles to run in a different image/machine, and... well I  
could probably go on.

JIT really has been tied to a very limited concept of "oh I need  
this, let's compile something, er, now where was I?" approach. The  
compiler has to be internal to the VM and so far as I'm aware is  
pretty much tied to C/C++ or worse.

Exupery is CALIL - Compile At Leisure, Install Later. Oh, and you  
could even  have setup where an external compiler-server caches a lot  
of methods and avoids even doing the compile a lot of the time.


tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
User: A harmless drudge.