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perlmod-perlmod-perl2

Strange behavior of '\' under mod_perl

I have the following in a script that runs under mod_perl

Logger::log("\$1 = '$1'");
Logger::log("\$ 1 = '$1'");
Logger::log("\\$1 = '$1'");

Which outputs the following into my log file:

logger:  = ''
logger: $ 1 = ''
logger: \ = ''

$1 is known to be null. Is this a bug in mod_perl2 or is it something else I'm missing?

Solution

  • Did you try:

    Logger::log(q!$1 = '! . $1 . q!'!);

    or, to avoid warnings:

    Logger::log(q!$1 = '! . ( defined $1 ? $1 : '' ) . q!'!);

    The idea here is that q!...! doesn't interpolate its contents, so you know for sure the first part of the string will be $1 = ". If it's still not appearing in the output, then you know Logger::log() or something it calls is interpolating its arguments, which probably shouldn't happen.

    Oh, and if you're using a more modern Perl, the second example can use ( $1 // '' ) instead.