Active Oberon Language Report Update 2019

Post by microtherion » Sun, Nov 17, 2019, 9:30 PM UTC

ainar-g wrote: post #18

vbezhenar wrote: post #15

Earlier quoted context omitted.

You can easily emulate break with conditional variable.

Of course, but wouldn't that effectively defeat the purpose of removing BREAK/EXIT in the first place? With something like: WHILE ~(lastIteration) & ~(Found(haystackPart, Needle)) DO (* Advance the haystackPart. *) END; I can at least say that after the loop if lastIteration is true, then the needle wasn't found in the haystack. While something like WHILE ~(found) DO (* Stuff. *) END; Conveys next to no information.…

Post by gmfawcett » Sun, Nov 17, 2019, 10:28 PM UTC

ainar-g wrote: post #6

(Only tangentially related to the OP, but what the hell.) Does anyone here have an experience programming in Oberon-07? One of the most interesting features of the language for me is the fact that it doesn't have a BREAK statement. Which means that one must use a form of WHILE for linear searches. Probably to force people to think in terms of structured programming instead of the logic of “hidden GOTOs”. Does it ever…

Post by bhaak » Mon, Nov 18, 2019, 2:42 PM UTC

ainar-g wrote: post #26

bhaak wrote: post #19

Earlier quoted context omitted.

An elegant solution (if applicable) is placing a deliberate sentinel value at the end of your data before looping. https://en.m.wikipedia.org/wiki/Sentinel_value Whereas usually loops have 2 tests for checking if the while loop should end (end-of-data-reached? or break-condition-is-true?) you only need to check for the latter. This is a very Oberonesque programming optimization.

I'm sorry, but I don't see how that answers my question. Oberon-07 has real FOR loops over arrays, so it doesn't need sentinel values. My question was about an idiom like: WHILE True DO (* Stuff. *) IF someCondition THEN EXIT; END; (* More stuff. *) END;