CXT105@psuvm.psu.edu (Christopher Tate) (04/17/91)
There seem to be all manner of interesting things floating around in the
internaldict, such as the FlxProc array and the superexec operator. But
does anyone know (or is anyone allowed to tell?) what operators such as
ErodeSW, CCRun, xlck, or ylck do?
I don't necessarily care whether they're actually *useful*; I'm just
curious about the innards of my LaserWriter....
I'm also assuming that the operators such as @repeat, @rfor, @loop, @ifor,
etc. have to do with low-level implementation of the interpreter. Is this
even close to right?
-------
Christopher Tate | "Excuse me, is this your bag?"
| "No."
cxt105@psuvm.psu.edu | "Are you sure? Do take your time."
{...}!psuvax1!psuvm.bitnet!cxt105 | "This is definitely *not* my bag."
cxt105@psuvm.bitnet | "Just as we thought...."andrew@visix.com (Andrew Bernard) (04/18/91)
In article <91106.223204CXT105@psuvm.psu.edu> CXT105@psuvm.psu.edu (Christopher Tate) writes: >There seem to be all manner of interesting things floating around in the >internaldict, such as the FlxProc array and the superexec operator. But >does anyone know (or is anyone allowed to tell?) what operators such as >ErodeSW, CCRun, xlck, or ylck do? > Some of these sound like hinting operators/procedures. Check out the Adobe Type 1 Font Format documentation. I don't know the others. >I don't necessarily care whether they're actually *useful*; I'm just >curious about the innards of my LaserWriter.... > >I'm also assuming that the operators such as @repeat, @rfor, @loop, @ifor, >etc. have to do with low-level implementation of the interpreter. Is this >even close to right? > These are the run-time forms of the looping operators. Basically, when you execute certain control operators (_repeat_, _for_, etc) they push some state information and your procedure onto the execution stack followed by one of the @ operators. The @ operator is then responsible for executing the procedure and generating the next iteration of the loop. This makes it possible for the interpreter to implement control structures without having to re-enter itself, which can be very expensive (though it does do this during things like _pathforall_). Using @ operators also makes recovery from things like _stop_ somewhat cleaner. I suspect it also helps a little when you want to implement multiple threads ala DPS. -- andrew bernard ring the doorbell on your mind software engineer but it's locked from the outside visix software -dinosaur jr. andrew@visix.com
woody@chinacat.Unicom.COM (Woody Baker @ Eagle Signal) (04/18/91)
In article <91106.223204CXT105@psuvm.psu.edu>, CXT105@psuvm.psu.edu (Christopher Tate) writes: > ErodeSW, CCRun, xlck, or ylck do? > The Type 1 Font book (the Black Book) explains most of these details. it does not cover superexec. Superexec is just like exec, except that it bypasses a majority of the invalid access errors. The simplest way to use it is to enclose a sequence of operations in { } and feed that to superexec. Nearly everything that will raise an invalid access error will work. > > ------- > Christopher Tate | "Excuse me, is this your bag?" > | "No." > cxt105@psuvm.psu.edu | "Are you sure? Do take your time." > {...}!psuvax1!psuvm.bitnet!cxt105 | "This is definitely *not* my bag." > cxt105@psuvm.bitnet | "Just as we thought...."