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Re: Re: regex substitution

by coolmichael (Deacon)
on Nov 05, 2001 at 10:40 UTC ( #123288=note: print w/replies, xml ) Need Help??

in reply to Re: regex substitution
in thread regex substitution

Perhaps it shouldn't work without /e, but it does, at least with activestate perl 5.6.1. (obviously, you should use strict and warnings...)
#!perl $_="this is a #fish#\n"; $a{"fish"}="test"; print; s/#(\w+)#/$a{$1}/; print; this is a #fish# this is a test C:\perl -v This is perl, v5.6.1 built for MSWin32-x86-multi-thread (with 1 registered patch, see perl -V for more detail) Copyright 1987-2001, Larry Wall Binary build 626 provided by ActiveState Tool Corp. http://www.ActiveS Built 01:31:15 May 2 2001

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(crazyinsomniac) Re^3: regex substitution
by crazyinsomniac (Prior) on Nov 05, 2001 at 13:03 UTC
    Have you read what the /e switch does? I sugguest you do.

    Your argument basically boils down to s/#(\w+)#/$variable/; in which $variable gets expanded, as it will no matter what (if /e is there or not).

    Compare this to:

    #!perl -w use strict; my %hashola = (fish => "test" ); sub f($){ return $hashola{shift @_}; } my $rock = "this is a #fish#\n"; my $block = $rock; print $rock; $block =~ s/#(\w+)#/&f($1);/; # expands $1, doesn't call &f print $block; $block = $rock; # restoree $block =~ s/#(\w+)#/$hashola{$1}/; # expands the variable print $block; $block = $rock; # restoree $block =~ s/#(\w+)#/&f($1)/e; # calls the function print $block; $block = $rock; # restoree $block =~ s/#(\w+)#/$hashola{$1}/e; print $block; $block = $rock; # restoree __END__ F:\dev>perl f this is a #fish# this is a &f(fish); this is a test this is a test this is a test F:\dev>
    Ok ok, from perlop (since s is an operator), I quote:
    e Evaluate the right side as an expression.
    Unless you escape $hashname{$1} like \$hashmane{$1}, the actual variable will be expanded independent of /e, as such is the nature of the s operator.

    Disclaimer: Don't blame. It came from inside the void

    perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"

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