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Re^3: Windows and backslashes and replacements oh my!

by The Perlman (Scribe)
on Jun 19, 2021 at 09:34 UTC ( #11134022=note: print w/replies, xml ) Need Help??


in reply to Re^2: Windows and backslashes and replacements oh my!
in thread Windows and backslashes and replacements oh my!

${bs}${bs} means using two consecutive backslashes, which is still weird.

Looks like somewhere a Unix tool like bash or another Perl is processing the file.

(Update: Obviously Perl needs to escape the backslash inside a regex)

FWIW: using $b2=chr(92)x2 might save you some typing

- Ron
  • Comment on Re^3: Windows and backslashes and replacements oh my!

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Re^4: Windows and backslashes and replacements oh my!
by LanX (Sage) on Jun 19, 2021 at 10:47 UTC
    One $bs is sufficient in my tests:

    d:\>perl -E"for $x (qw/C:\berrybrew\test C:\berrybrew /) {$_=$x; $bs=c +hr(92); s/berrybrew(?!\\+test)/berrybrew${bs}test/; say}" C:\berrybrew\test C:\berrybrew\test d:\>

    > Obviously Perl needs to escape the backslash inside a regex

    not after interpolation of variables like $bs

    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery

      > > Obviously Perl needs to escape the backslash inside a regex

      > not after interpolation of variables like $bs

      I have to correct myself, it depends on the side of the substitution

      • the right side is a simple doublequoted string, so after interpolation no escaping
      • but the left side is a regex with two levels of escaping
        1. string interpolation with escaping first, i.e. \$bs won't be interpolated
        2. regex interpretation with escaping first, i.e. /\*/ is not a quantifier but literal * same with /$bs*/
      compare
      d:\>perl -E"for $x (qw/C:\berrybrew\test C:\berrybrew /) {$_=$x; $bs=c +hr(92); s#$bs$bs#<${bs}>#g; say}" C:<\>berrybrew<\>test C:<\>berrybrew d:\>

      or to eliminate the Win command line

      use v5.12; use warnings; use Data::Dump; my $bs=chr(92); for my $x (qw/C:\berrybrew\test C:\berrybrew /) { $_=$x; s#$bs$bs#<${bs}>#g; say; #ddx $_; } $_='$bs'; s/\$bs/<$&>/; say;
      C:<\>berrybrew<\>test C:<\>berrybrew <$bs>
      so this might be the OPs original problem

      see also

      s/RegEx/substitutions/: Variable interpolation and when to use /e - modifiers

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery

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