Re: regex compilation

/$regex2/ will have the same interpolation as qr/$regex2/, so we can look more closely at what you are getting by examining the resulting regex2 object:

my $regex1 = qr/(?:(?|(?:\")([^\\\"]*(?:\\.[^\\\"]*)*)(?:\")))/;
my $regex2 = qq/(?:(?|(?:\")([^\\\"]*(?:\\.[^\\\"]*)*)(?:\")))/;

print $regex1, "\n", qr/$regex2/, "\n";
[download]

The output:

(?^:(?:(?|(?:\")([^\\\"]*(?:\\.[^\\\"]*)*)(?:\"))))
(?^:(?:(?|(?:")([^\"]*(?:\.[^\"]*)*)(?:"))))
[download]

The single quoted construct is gobbling the escapes.

Dave

Comment on Re: regex compilation Select or Download Code

Replies are listed 'Best First'.
Re^2: regex compilation by AnomalousMonk (Archbishop) on Feb 12, 2019 at 20:29 UTC
FWIW, single-quoted regex notation gets you closer (update: than double-quoting) to the desired final form, but still not all the way and there are some pitfalls. Better, IMHO, to stick to `qr//`. (BTW: morgon: It's not necessary to escape a `"` (double-quote) in a `qr//` expression.) File `rx_qr_qq_q_1.pl`: `use warnings; use strict; my $rx_qr = qr/(?:(?\|(?:\")([^\\\"](?:\\.[^\\\"]))(?:\")))/; my $rx_qq = qq/(?:(?\|(?:\")([^\\\"](?:\\.[^\\\"]))(?:\")))/; my $rx__q = q/(?:(?\|(?:\")([^\\\"](?:\\.[^\\\"]))(?:\")))/; print qq{raw qr: $rx_qr \n}; print qq{qr/qq/: }, qr/$rx_qq/, "\n"; print qq{qr/q/ : }, qr/$rx__q/, "\n";` [download] Output: `c:\@Work\Perl\monks\morgon>perl rx_qr_qq_q_1.pl raw qr: (?-xism:(?:(?\|(?:\")([^\\\"](?:\\.[^\\\"]))(?:\")))) qr/qq/: (?-xism:(?:(?\|(?:")([^\"](?:\.[^\"]))(?:")))) qr/q/ : (?-xism:(?:(?\|(?:\")([^\\"](?:\.[^\\"]))(?:\"))))` [download] Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]
Re^2: regex compilation by morgon (Priest) on Feb 12, 2019 at 18:05 UTC
Neat trick, thanks a lot. So I need to double all the backslashes.	[reply]
Re^3: regex compilation by AnomalousMonk (Archbishop) on Feb 12, 2019 at 18:31 UTC
So I need to double all the backslashes. I would say that you need to use `qr//` to build `Regexp` objects. These objects behave essentially like strings in the situations in which you seem to be interested in using them. Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]
Re^3: regex compilation by Laurent_R (Canon) on Feb 12, 2019 at 18:51 UTC
So I need to double all the backslashes. Probably not. I think that you need to use `qr//`	[reply] [d/l]


Pathologically Eclectic Rubbish Lister
	PerlMonks