On 04.09.2020 15:51, Mike Cowlishaw wrote: > I think you all know my opinion on weird notations in languages that are only > known and used by a > few 'elite' programmers -- yet are all-too-easily misunderstood by > less-practiced (or simply > less-able or infrequent) programmers...
Yes, I think everyone concurs. However, the question still remains, if one wishes to add the ability to short-circuit to Rexx (like programmers coming from C/++/#, Java etc are accustomed to and surprised that this concept is not available in Rexx), how to do it. Currently Rick added the comma as a delimiter indicating a short-circuit using and concatenations. Then, if short-circuiting or concatenations should be supported, how to allow them to be expressed in a "Rexxish" manner that is not only known to a few 'elite' programmers, but anyone who comes from C/++/# or Java? ---rony > > > ---------------------------------------------------------------------------------------------------- > *From:* Erich Steinböck [mailto:erich.steinbo...@gmail.com] > *Sent:* 04 September 2020 14:22 > *To:* Open Object Rexx Developer Mailing List > *Subject:* Re: [Oorexx-devel] Short cutting logical operators > > You're right. > I've often wondered whether a method call really *must* evaluate all its > arguments upfront. > What about lazy evaluation? Only evaluate an argument when it is actually > required, i. e. > accessed for the first time? > > On Fri, Sep 4, 2020 at 3:17 PM Rick McGuire <object.r...@gmail.com > <mailto:object.r...@gmail.com>> wrote: > > Hmmm, I found an awkward bit with this proposal. For the operators, > these are all > transformed into method calls under the cover, so "a | b" gets > executed as "a~'|'(b)", > where the object on the left hand side does the evaluation of the > condition. This allows > any class to override the '|' and '&'. With the overrides, the > evaluation needs to be > handled directly by the operator code because there's no way to delay > evaluation of a > method argument, and it would be very difficult to allow something > like that to exist. I'm > not sure I'm comfortable with '*|' and '*&' be special cases as > operators. > > Rick > > On Fri, Sep 4, 2020 at 9:03 AM Rick McGuire <object.r...@gmail.com > <mailto:object.r...@gmail.com>> wrote: > > There's been a bit of a discussion about the short-cutting > conditional lists > implemented by IF, WHEN, et al. I find that construct very > useful, but as the > discussion on the list has revealed, it has its limitations. > > It would actually be fairly trivial to implement AND and OR > operators that can do > short-cut evaluation. Of course, this is not possible for XOR, > which always requires > both values. The real questions are 1) should it be done and 2) > what should the > operator be. I've been tentatively using *& and *| in my thinking > about this, but > there are certainly other possibilities. > > Rick >
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