[REBOL] Re: Threading continued
From: maarten:vrijheid at: 30-Jan-2004 8:38
Hi Joel,
>Sort of like iterating DO/NEXT with an additional check for REST ?
>
Yes.
>I pondered doing something with DO/NEXT a while back, but gave up in
>frustration (I hope you're smarter and/or more patient than I ;-) as
>I want to be able to write expressions/functions more sophisticated
>than a single block, but still have interruptability. For example:
>
> eval [
> foreach line read/lines %somefile [
> print line
> rest
> ]
> ]
>
>Or
>
> interruptableFunction: func [aLine [string!]] [
> print aLine
> doSomethingInteresting aLine
> rest
> ]
>
> eval [
> foreach line read/lines %someOtherFile [
> interruptableFunction line
> ]
> ]
>
>You said "takes a block" so I inferred that things such as the above
>(nested blocks, including function evaluation) are currently out of
>reach. Am I too pessimistic?
>
Yes and no. Right now, if rest is returned as value of a subexpression,
this works nicely. All three code pieces work, but I because I am patching
all looping and conditional constructs (to set all kinds of hidden flags
for rest and eval).
More patient I guess :-)
>If I have to do all the work of managing e.g. loops and other "control
>structures", including functions, I think I'd probably want to just go
>ahead and evert the code into a task object (per the article on
>REBOLforces) with a STEP method that does some meaningful (but not over
>long) piece of work and then saves state and returns control.
>
I agree. Transparancy is the way to go. Once I get some stuff in a
decent state I'll need others to test it and see if it works "naturally"
--Maarten<
