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From: Brian Dickson <brian.peter.dickson@gmail.com>
Date: Thu, 30 Mar 2017 19:07:28 -0500
Message-ID: <CAH1iCiouKZYAtdpSPNEK+fy-O8UQZbEf5O8sH-+zJqUhZdwvGA@mail.gmail.com>
To: "dnsop@ietf.org WG" <dnsop@ietf.org>
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Archived-At: <https://mailarchive.ietf.org/arch/msg/dnsop/QCraribgw0d6BjYtDiqONZWrBy8>
Subject: [DNSOP] Microphone question on back-references - BULK RR
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>
> Apologies but I did not hear the full question regarding BULK RR=E2=80=99=
s and the
> perl like back-references.  If you could please repeat the question we
> would be happy to comment.
>
>
>
>
>
> Thanks,
>
> John
>

Sorry for the delayed response.

The question was:

Given the use of perl-style back-references ( like "${1}" ) - would it not
make sense to use the same perl syntax to provide well-defined targets for
those back-references?

E.g. "my-special-(<regex-thing>)-(<regex-thing>)-with-suffix" and then
there is no ambiguity as to what ${1} and ${2} point at?

Perl regex rules are IMHO very clean and clever, and avoid ambiguity very
nicely.
(Also historical shout-out to Henry Spencer, whose regex mods served as the
source for perl's.)

Things inside parentheses are the target of back-refs.
In Perl, there is no need to escape the parentheses within regexes.

Brian

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<div dir=3D"ltr"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px =
0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><p class=
=3D"MsoNormal" style=3D"color:rgb(0,0,0);font-family:times;font-size:medium=
">Apologies but I did not hear the full question regarding BULK RR=E2=80=99=
s and the perl like back-references.=C2=A0 If you could please repeat the q=
uestion we would be happy to comment.<span></span></p><p class=3D"MsoNormal=
" style=3D"color:rgb(0,0,0);font-family:times;font-size:medium"><span>=C2=
=A0</span></p><p class=3D"MsoNormal" style=3D"color:rgb(0,0,0);font-family:=
times;font-size:medium"><span>=C2=A0</span></p><p class=3D"MsoNormal" style=
=3D"color:rgb(0,0,0);font-family:times;font-size:medium">Thanks,<span></spa=
n></p><p class=3D"MsoNormal" style=3D"color:rgb(0,0,0);font-family:times;fo=
nt-size:medium">John</p></blockquote><div><br></div><div>Sorry for the dela=
yed response.</div><div><br></div><div>The question was:</div><div><br></di=
v><div>Given the use of perl-style back-references ( like &quot;${1}&quot; =
) - would it not make sense to use the same perl syntax to provide well-def=
ined targets for those back-references?</div><div><br></div><div>E.g. &quot=
;my-special-(&lt;regex-thing&gt;)-(&lt;regex-thing&gt;)-with-suffix&quot; a=
nd then there is no ambiguity as to what ${1} and ${2} point at?</div><div>=
<br></div><div>Perl regex rules are IMHO very clean and clever, and avoid a=
mbiguity very nicely.</div><div>(Also historical shout-out to Henry Spencer=
, whose regex mods served as the source for perl&#39;s.)</div><div><br></di=
v><div>Things inside parentheses are the target of back-refs.=C2=A0</div><d=
iv>In Perl, there is no need to escape the parentheses within regexes.<br><=
/div><div><br></div><div>Brian</div></div>

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