Rereading A03, I ran across the original reasoning behind why Perl 5's '?:' trinary operator became '?? ::' first, and then '?? !!'. Three reasons were given:
* the '?' and ':' tokens are far too broadly useful to be gobbled up by the trinary operator. * the doubled symbols bring to mind the short-circuiting operators (e.g., '&&' and '||'), suggesting a similar short-circuiting behavior here. * the '!!' brings to mind "evaluate this when the condition fails". IMHO, the first point was always more about the ':' than it was about the '?'; if you were to replace ':' with '!', I suspect that this concern would largely go away. That is, I don't see any infix:<?> or infix:<!> operators in the current draft. A case could be made that a trinary '... ? ... ! ...' operator could work within the current state of things without conflict. Also, the whitespace disambiguation rules that were later implemented go a long way to resolving the original problem of ':' trying to do too much. That said, the latter two points are still valid. '... ? ... : ...' might be perfectly workable; but so is '... ?? ... !! ...'. However, there still may be room for improvement. Consider the following possibility: Instead of being a single, inflexible trinary operator, break this into a pair of binary operators: infix:<??> and infix:<!!>. Each can be used on its own, returning the right side if the condition evaluates as expected (i.e., true for ?? and false for !!), and otherwise returns 'undef'. A variation of chaining associativity gets used, with the "chaining rule" being '$v1 op1 $v2 // $v1 op2 $v3' instead of '$v1 op1 $v2 && $v2 op2 $v3', as is the case for comparison chaining. So all of the following would be valid syntax: $test ?? $a !! $b # true: $a; false: $b $test !! $a ?? $b # true: $b; false: $a $test ?? $a # true: $a; false: undef $test !! $b # true: undef; false: $a I suggest this mainly because it's potentially more extensible than the current model. I could see someone devising a "fuzzy logic" module which could allow for such things as: $test ?? $a !! $b maybe $c likely $d unlikely $e -- Jonathan "Dataweaver" Lang
