Re: [Alephmodular-devel] Input architecture (ActionFlags)

[Timothy C. <tco...@ha...>]

>>> Well, my initial fears of messing with the action flags involve 
>>> breaking the M2 Films. If you're going to talk about changing how 
>>> the action flags are stored, then you better detail how to identify 
>>> and handle replays from different versions of the code. I don't care 
>>> so much if our films don't run under Marathon, but we should be able 
>>> to handle theirs, always.
>>
>> Yeah simple, the code that handles a replay examines the file, 
>> determines that it's a "traditional" film file, and sets up to use 
>> the MarathonFilmUnpacker.  Same deal on output (just use a 
>> MarathonFilmPacker, which writes M2-compatible films, when starting 
>> up a MarathonGame).
>
> Given the importance of this, I want more detail than this. This 
> cannot be a "magic happens here." I want to know *how* you determine 
> it to be what kind of film file it is.
>

One relatively simple way (I think) would be to give our new, 
M2/Inf-incompatible film format a header telling what version of film 
it is.  Thus, the first thing AM can do when opening a film is to look 
for this header.  If it's there, treat it as the version it says it is. 
  If it's not, attempt to open it as an M2 film.  (Obviously, it'll get 
into trouble if, say, someone tries to open their word processing 
document as a film, but I don't think we need to worry too much about 
that kind of really dumb behaviour :-)

Timothy Collett

"But what ... is it good for?"
--Engineer at the Advanced Computing Systems Division of IBM, 1968, 
commenting on the microchip