At 11:46 AM +0100 10/29/02, Juergen Boemmels wrote:
No, it doesn't. It needs to preallocate a few entries in the TOC at the start of the chunk, but that's it. Not that much waste, even if some of the metadata's in the TOC.Dan Sugalski <[EMAIL PROTECTED]> writes:Well, on thinking a bit about this, there's no reason that we have to worry--it's perfectly OK for us to declare, unconditionally, that segment 0 is always bytecode, 1 line number info, and so on, with everything after position X (for some value of X) left up in the air. A bit dodgy, true, as it means that any new known segment types we add in will be floating, but I don't think we're going to end up with too many performance-critical pieces in the bytecode. (Arguably it's just the bytecode itself, the symbols, and the constants, as the rest are looked at under exceptional circumstances or on (rare) demand)*No* This really kills extendability, or makes it at least very ugly. It needs to prealloc a certain number of segments.
The point is to have a file format that does what we need it to--present executable bytecode data to the interpreter--as fast as possible. Everything else is secondary to that. The rest of the metadata's needed, so it's there, but access to it doesn't need to be as fast.
Yes, it'll only be a few microseconds, but it's a few microseconds versus a few bytes in the file. Disk space is less dear than cycles.
Sure, but bell-bottoms are in, people drink absinthe, and there are folks that do street luge in San Francisco. Just because it's done by other systems doesn't make it the right answer.Each of this has a fixed semantic. Extending means consuming on of the preallocated fields, or using some segment beyond the preallocated area but then it needs a type field. In fact the preallocated segments also have a type-field: the position in the packfile. I'm fine with a numeric type for the core, and have some extension type with named types if it is a speed issue, but I really dont like this positional approach. BTW: COFF and ELF use named sections.
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Dan
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