Piers Cawley wrote:
> If I replace C<< ($key, $val) >> with
>
> @ary = m/<$pattern>/
>
> and the match succeeds, how many elements are there in @ary?
Zero. No explicit captures in that pattern.
> Suppose you want to use a hypothetical variable to bind a name to
> a capture:
>
> / (\S+) { let $x := $1 } /
>
> A shorthand for that is:
>
> / $x:=(\S+) /
>
> The parens are number independently of any name, so $x is an alias
> for $1.
>
> And it's that last sentence that's important here. So, it looks like
> C<< +@ary >> is going to be 4.
No. Only explicit paren captures add to the array attribute of the match object.
Implicit or explicit named captures add to the *hash* attribute of the match object.
> m: w / $2:=(\S+) <lt>= $1:=(\S+) /
>
> Note that, left to their own devices, those grouping parentheses would
> generate the $1 and $2 in the order given.
> Now, assignment to hypotheticals doesn't happen all at once, it
> happens when the matching engine reaches that point in the
> string. Unless I'm very much mistaken, the order of execution will
> look like:
>
> $2:=$1; $1:=$2;
>
> And it seems to me that we'll end up with $1 and $2 both bound to the
> same string; which isn't working quite how I expect. Or do we special
> case the occasions when we bind the result of a capturing group to a
> numeric match variable?
That's my understanding. If you *explicitly* bind a captured group to a
numbered hypothetical, then the capture doesn't also implicitly bind to
a numbered hypothetical.
Damian
