Another interesting thing is that if this is implemented, then it will make it
possible to use ? in other places where <colonpair> is used. For example, it
will allow %h<x>:?exists . It seems that it will also affect character classes
(e.g. <:?Ll>). Some of these totally make sense, some not so much. But we
already have :!delete and nobody seems to be complaining :)
There's also <quotepair> which has very similar logic, it does support ! but
does not support ? (e.g. m:!i/ … / but no m:?i/ … /). I wonder, if <colonpair>
is ever touched, should the same thing be done with <quotepair> also?
On 2017-07-22 23:40:53, alex.jakime...@gmail.com wrote:
> For those who don't agree that there is a connection between ? and !…
> Actually,
> there are some other places where ?↔! connection is implied. In fact,
> I will
> probably never list all of them.
>
> In regexes:
> * <?> always succeeds, <!> always fails (and no question implied)
> * <?{ … }> <!{ … }> tests for truthy and falsey values. Note that <{}>
> does
> something completely different.
> * a+? is for non-greedy, a+! for greedy (again no question implied)
> * <before>, <?before>, <!before> (note that all three are supported,
> same goes
> for <after>)
>
>
>
> I would also do the job for the other side and provide some counter
> examples:
> * There is a ! metaop but no ? metaop (e.g. !== but no ?==). If there
> was one,
> it would practically be a noop because you wouldn't be able to use it
> on
> anything non-iffy anyway. That said, it's still a weird case.
> * There is [foo]? in regexes but no [foo]! . At first I thought that
> this is
> intentional, given that ! may be needed for something else eventually,
> but
> knowing that a+! works I'm no longer sure.
>
> This raises a question: well… should we implement these too? Maybe
> this: “If
> you’re gonna generalize, do it harder, but not too hard.”[^1] is
> relevant here,
> but maybe not.
>
> Bonus:
> * In some cases the use of ? or ! is not related to this issue at all.
> e.g.
> private methods (if we allow some things to have no opposites, why
> bother at
> all?)
>
>
> Anyway, that's some good food for thought I think.
>
> [1] https://perl6advent.wordpress.com/2014/12/24/day-24-seeing-wrong-
> right/
