Documentation patch for -M

[p5pRT]

Migrated from rt.perl.org#133961 (status was 'open')

Searchable as RT133961$

[p5pRT]

From book@cpan.org

Here's a tiny documentation patch for -M.

I found this while and reading `perlrun` and exploring the possibilities
of `-M5;some-code` as a way to insert code before the loop when used in
combination with -n and -p (book/perlsecret#16).

  $ perl -MO=Deparse '-M5;insert_code_here()' -pe 1
  sub BEGIN {
  require 5;
  ()
  }
  insert_code_here();
  LINE​: while (defined($_ = readline ARGV)) {
  '???';
  }
  continue {
  die "-p destination​: $!\n" unless print $_;
  }
  -e syntax OK

Feel free to reword it as needed.

--
Philippe Bruhat (BooK)

Destroy the little and you destroy the large.
  (Moral from Groo The Wanderer #55 (Epic))

[p5pRT]

From book@cpan.org

0001-Document-a-way-to-perform-use-Module-VERSION-LIST-on.patch

From 832c0a61e398ca47fc96eed3573c061ff8ba880d Mon Sep 17 00:00:00 2001
From: "Philippe Bruhat (BooK)" <book@cpan.org>
Date: Wed, 27 Mar 2019 09:00:24 +0100
Subject: [PATCH] Document a way to perform `use Module VERSION LIST` on the
 command-line

The `split(/,/,q{foo,bar})` seems to still happen.

This is the currently documented case:

    $ perl -MO=Deparse '-MList::Util=any,all' -e1
    use List::Util (split(/,/, 'any,all', 0));
    '???';
    -e syntax OK

And these work too (and the split on comma also happens somehow):

    $ perl -MO=Deparse '-MList::Util any,all' -e1
    use List::Util ('any', 'all');
    '???';
    -e syntax OK

    $ perl -MO=Deparse '-MList::Util 1.5' -e1
    use List::Util 1.5;
    '???';
    -e syntax OK

    $ perl -MO=Deparse '-MList::Util 1.5 any,all' -e1
    use List::Util 1.5 ('any', 'all');
    '???';
    -e syntax OK
---
 pod/perlrun.pod | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/pod/perlrun.pod b/pod/perlrun.pod
index 77660ef17d..4855c29d81 100644
--- a/pod/perlrun.pod
+++ b/pod/perlrun.pod
@@ -692,6 +692,11 @@ is that B<-MI<MODULE>=number> never does a version check,
 unless C<I<MODULE>::import()> itself is set up to do a version check, which
 could happen for example if I<MODULE> inherits from L<Exporter>.
 
+However, it should be noted that since the syntax C<'-MI<MODULE foo,bar>'>
+shown above will generate C<use MODULE ('foo', 'bar')>, it's possible
+to do a version check using C<'-MI<MODULE VERSION foo,bar>'>, which will
+generate C<use MODULE VERSION ('foo', 'bar')>.
+
 =item B<-n>
 X<-n>
 
-- 
2.20.1

[p5pRT]

From @jkeenan

On Wed, 27 Mar 2019 08​:56​:54 GMT, book wrote​:

Here's a tiny documentation patch for -M.

I found this while and reading `perlrun` and exploring the possibilities
of `-M5;some-code` as a way to insert code before the loop when used in
combination with -n and -p (book/perlsecret#16).

$ perl \-MO=Deparse '\-M5;insert\_code\_here\(\)' \-pe 1
sub BEGIN \{
    require 5;
    \(\)
\}
insert\_code\_here\(\);
LINE​: while \(defined\($\_ = readline ARGV\)\) \{
    '???';
\}
continue \{
    die "\-p destination​: $\!\\n" unless print $\_;
\}
\-e syntax OK

Feel free to reword it as needed.

If we accept the patch, then this becomes a feature which we have to support going forward. Do we want to do that? Should we?

Thank you very much.
--
James E Keenan (jkeenan@​cpan.org)

[p5pRT]

The RT System itself - Status changed from 'new' to 'open'

[p5pRT]

From book@cpan.org

On Wed, 27 Mar 2019 05​:24​:28 -0700, jkeenan wrote​:

If we accept the patch, then this becomes a feature which we have to
support going forward. Do we want to do that? Should we?

My understanding of many of the command-line operators like -p, -n, -e
and others is that they basically construct a string that ends up being
eval'ed. This is a particularly stable part of Perl.

This powers the Eskimo Greeting secret operator `}{` and makes weird
things like `perl -pe '11..&'` (exposed back in 2001) still work today.

https://metacpan.org/pod/perlsecret#Eskimo-greeting
https://www.nntp.perl.org/group/perl.fwp/2001/12/msg813.html
http​://web.archive.org/web/20020715001632/http​://use.perl.org/~pdcawley/journal/1474

-- BooK

[jkeenan]

From book@cpan.org

On Wed, 27 Mar 2019 05​:24​:28 -0700, jkeenan wrote​:

If we accept the patch, then this becomes a feature which we have to
support going forward. Do we want to do that? Should we?

My understanding of many of the command-line operators like -p, -n, -e and others is that they basically construct a string that ends up being eval'ed. This is a particularly stable part of Perl.

This powers the Eskimo Greeting secret operator }{ and makes weird things like perl -pe '11..&' (exposed back in 2001) still work today.

https://metacpan.org/pod/perlsecret#Eskimo-greeting https://www.nntp.perl.org/group/perl.fwp/2001/12/msg813.html http​://web.archive.org/web/20020715001632/http​://use.perl.org/~pdcawley/journal/1474

-- BooK

@book, if you want to move this patch forward, could you file a pull request?