On 06.09.2020 20:52, WalterPachl wrote:
... cut ...
> so the commas are ands with shortcut
>
> Rony's notation seems clear/er/ &, and |,
>
Well, it was Erich suggesting them as a possibility, I just spelled the effect
out:
On 05.09.2020 20:39, Rony G. Flatscher wrote:
> On 04.09.2020 15:17, Erich Steinböck wrote:
>> I'm in favor of this proposal.
>> To follow our existing shortcut-style with commas (note that although
almost all of our
current comma-shortcuts are AND-style, we also have an OR-style
comma-shortcut for a WHEN in a
SELECT CASE) we might use and-comma (&,) and or-comma (|,) as operators.
>
> As Rick allows the comma "," to indicate short-circuiting conjunctions,
then this could be
seen as a short version of "&," taking the '&' as optional in this case.
Using "|," for a
short-circuiting disjunction would then be logical :).
>
> So samples might look like:
>
> -- conjunction:
> if a=.true , b=.false , c=.true then ...
>
> if a=.true &, b=.false &, c=.true then ... -- same as above
>
> -- disjunction:
> if a=.true |, b=.false |, c=.true then ...
>
> In this case the comma after the logical operator indicates
short-circuiting.
>
> This mostlikely can be understood by students who get exposed to this
notation (just needing
to memorize that a trailing comma indicates short-circuiting for
conjunctions and disjunctions).
>
> So in favor for this suggested syntax: +1
>
> ---rony
Starting out with the standard Rexx conjunctions and disjunctions:
if a=.true & b=.false & c=.true then ... -- classic Rexx, all expressions
get evaluated
if a=.true | b=.false | c=.true then ... -- classic Rexx, all expressions
get evaluated
Introducing a trailing comma after a logical operator to indicate a
short-circuit evaluation would
look like:
if a=.true &, b=.false &, c=.true then ... -- short-circuit if an
expression yields .false
if a=.true |, b=.false |, c=.true then ... -- short-circuit if an
expression yields .true
This way the logical operators remain and the trailing comma indicates a
short-circuit where the
programmer desires it. IMHO the comma is an eye-catcher here making it very
clear where a
short-circuit takes place.
As there are probably quite a lot of programs out there which use ooRexx 5
short-circuiting of
conjunctions, compatibility could be established by allowing the & logical
operator to be optional
in the case of a a short-circuit with commas only.
---rony
P.S.: Unfortunately, the semantics of comma-separated expressions in ooRexx
(short-circuit
conjunction) is not the same as in NetRexx (short-circuit disjunction).
However, if in ooRexx
short-circuiting is done supplying the logical operator then
misunderstandings/misconceptions can be
easily avoided as the logical operator could/would remain in place.
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