Strange behaviour of m and $

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I have a piece of code in which it seems like the m operator does not work properly. I am new to Perl, so I assume I'm doing something I shouldn't be. What do you think?
This is the output:

'fudge' does not match 'fudge'
[download]

of this:

use strict;

sub test_reg1
{
    return "fudge";
}

sub test_reg2
{
    print "'",$_,(/&test_reg1/i ? "' matches '" : "' does not match '"
+),&test_reg1,"'\n";
}

$_ = "fudge";
&test_reg2("fudge");
[download]

Comment on Strange behaviour of m and $_ Select or Download Code

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Re: Strange behaviour of m and $_ by Fletch (Bishop) on Oct 17, 2006 at 22:20 UTC
Subroutine invocations don't interpolate in double quoted strings (of which `m//` is a special kind). Either store the results from your function in a scalar and let that interpolate, or use something like `/@{[ test_reg1() ]}/` instead. And an aside, don't use the leading ampersand on subroutine calls; it does things to how the sub is called and unless you specifically have a reason to (and know why you're doing it) you should just omit it.	[reply] [d/l] [select]
Re^2: Strange behaviour of m and $_ by ysth (Canon) on Oct 18, 2006 at 00:10 UTC
And an aside, don't use the leading ampersand on subroutine calls; it does things to how the sub is called Slight clarification: that only applies when no () follow the sub name.	[reply]
Re^3: Strange behaviour of m and $_ by ikegami (Patriarch) on Oct 18, 2006 at 01:01 UTC
...except `$\=$/; sub print { CORE::print("[$_[0]]"); } print('foo'); # foo &print('bar'); # [bar]` [download]	[reply] [d/l]
Re: Strange behaviour of m and $_ by jeffa (Bishop) on Oct 17, 2006 at 22:17 UTC
Don't use global variables: `print( test_reg('fudge','fudge') ? "matches\n" : "no matches\n" ); sub test_reg { my $this = shift; my $that = shift; return $this =~ /$that/i; }` [download] jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply] [d/l]