Re^3: On error, how to show the regexp values? (tracing warnings)

[LanX]

?

> Even outside the debugger, you can establish a warnings handler:

Yes, since "for debugging" doesn't mean "inside debugger"

> And the reason $2 is undefined

see Re: On error, how to show the regexp values? (?: doesn't capture)

> has only one capture group, (\d).

capture groups are unrelated to \d

The outer parens would capture without the colon :

[Anonymous Monk]

>> has only one capture group, (\d).

> capture groups are unrelated to \d

Capture groups in general are unrelated to \d, but nonetheless the lone capture group in the regexp is (\d).

> The outer parens would capture without the colon :

Also correct. But in fact the outer parens do have the colon, so they do not capture.