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Re^2: Regexp substitution using variables

by AnomalousMonk (Bishop)
on Nov 26, 2020 at 09:50 UTC ( #11124251=note: print w/replies, xml ) Need Help??


in reply to Re: Regexp substitution using variables
in thread Regexp substitution using variables

Partly in answer to choroba's challenge, here's an approach that works with forward/backslashes, escape sequences and capture variables in replacement strings. Whether it will answer your needs is another question. A fixup step for forward slashes is necessary. Works under Perl versions 5.8.9 and 5.30.3.

Win8 Strawberry 5.8.9.5 (32) Thu 11/26/2020 4:08:05 C:\@Work\Perl\monks >perl use strict; use warnings; my $pattern = '(\\\\tEs/Ti//N\x67\\\)'; my $replacement = '\\\Fr/es//h\\\\ \U$1'; my $flags = 'i'; # $got_g is true if /g modifier present in flags. # ($flags, my $got_g) = sanitize_flags_detect_g($flags); fixup_forward_slashes($pattern, $replacement); my $value = 'My \Tes/ti//ng\ Text'; print "replacement '$replacement' \n"; my $eval_string = "\$value =~ s/$pattern/$replacement/$flags"; print "eval_string '$eval_string' \n"; eval $eval_string; print "eval err '$@' \n"; print "output '$value' \n"; sub fixup_forward_slashes { s{/}'\/'g for @_; } ^Z replacement '\\Fr\/es\/\/h\\ \U$1' eval_string '$value =~ s/(\\tEs\/Ti\/\/N\x67\\)/\\Fr\/es\/\/h\\ \U$1/i +' eval err '' output 'My \Fr/es//h\ \TES/TI//NG\ Text'
It's awkward that a \ single literal backslash in the input/output string must be represented by a \\ double backslash in the substitution and by \\\ triple or \\\\\ quadruple backslashes in the single-quoted pattern/replacement strings, but that's single/double-quotish backslash handling for ya. If the pattern/replacement strings were taken from a file, it would be possible to just use double backslashes.


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