Andreas Karlsson wrote:
> Hi guys,
Hello,
> I'm doing a script to search through a lot of files and doing some
> replacements.
> It is a lot of different replacements that has to be done so I list them in a
> .txt
> instruction file in two columns representing the strings to be matched and
> replaced
> and the new text.
> A problem arise when doing some more complex substitution, wanting to keep
> certain
> parts of a string while replacing others. To be specific in this case I want
> to
> remove the '' surrounding a string. The string between '' will change.
>
> The problem comes from that I want to use the \1 (or $1) variable but since
> the
> substitution command looks like
> $line=~ s/$subst_from/$subst_to/ig;
>
> and the $1 is incorporated into the $subst_to variable it is being populated
> when
> the replecement string is assinged to $subst_to.
> How can I keep the substitution command as general as I have it, always
> taking the
> same to variables but still making use of the $1,...,$9 feature of Perl?
> I post you a test-program which shows my problem.
> List.\1 being printed after 'Result:' is the problem.
>
> It's developed in an cygwin-environment and executes using the command
> perl PerlSubstituteProblem.pl
>
> The printouts looks like this when I run it:
>
> Script started.
> subst_to: List.\1
> '' should be removed in List.'123_KeepThis_123'
> $1_1: 123_KeepThis_123
> $1_2: 123_KeepThis_123
> Result:
> '' should be removed in List.\1
> Same thing but non-general s//:
> '' should be removed in List.123_KeepThis_123
> Changed in 1 places
>
>
> ________Program_______________
> #!/usr/local/bin/perl
> use strict;
> use strict 'refs';
> $|=1; #Flush ON
> print "Script started.\n";
>
> my($nr_of_changes,$line,$line_copy, $subst_from,$subst_to)=0;
>
>
> $subst_from="List\\.'(\\w*)'";
> $subst_to="List.\\1";
> print "subst_to: $subst_to \n";
>
> $line="'' should be removed in List.'123_KeepThis_123' \n";
> print "$line";
>
> if($line =~/$subst_from/i)
> {
> $line_copy=$line;
> print "\$1_1: $1 \n";
> $nr_of_changes++;
> $line=~ s/$subst_from/$subst_to/ig;
> print "\$1_2: $1 \n";
> print "Result: \n";
> print "$line";
>
> print "Same thing but non-general s//: \n";
> $line_copy=~ s/$subst_from/List.\1/ig;
> print "$line_copy";
>
> }
>
> print"Changed in $nr_of_changes places\n";
>
> exit(0);
$ perl -le'
my $subst_from = qr/(?<=List\.)\047(\w*)\047/;
my $subst_to = q/$1/;
my $line = qq/\047\047 should be removed in List.\047123_KeepThis_123\047 \n/;
print for $subst_from, $subst_to, $line;
my $nr_of_changes = $line =~ s/$subst_from/$subst_to/eeig;
print for $nr_of_changes, $line;
'
(?-xism:(?<=List\.)\047(\w*)\047)
$1
'' should be removed in List.'123_KeepThis_123'
1
'' should be removed in List.123_KeepThis_123
John
--
Perl isn't a toolbox, but a small machine shop where you can special-order
certain sorts of tools at low cost and in short order. -- Larry Wall
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