I was knocking my head against a bug in my code when I came across Perlish behavior I don't really understand. I reduced the code to the bare minimum to best show the behavior.

#!perl
use strict;
use warnings;
my $data = 'some
random
data
to
test
this';

while (my ($line) = $data =~ m/^(.*)$/gm)
{
    print "<0>" . $line ."\n";
}
[download]

The above code will output indefinitely:

<0>some
.
.
<0>some
<0>some
[download]

Now, if we modify the code just a little bit, we get the following code and behavior, which is what I wanted:

#!perl
use strict;
use warnings;
my $data = 'some
random
data
to
test
this';
while ($data =~ m/^(.*)$/gm)
{
    my $line = $1;

    print "<1>" . $line ."\n";
}
[download]

The above will output what I expect:

<1>some
<1>random
<1>data
<1>to
<1>test
<1>this
[download]

To get it out of the way, someone might say why don't I do the below instead? The behavior is the same as above. To avoid dirty details, yes, that's true. I just want to preserve $_ deeper within the while{} block

while ($data =~ m/^(.*)$/gm)
{
    print "<2>" . $1."\n";
}
[download]

Can someone explain why the first code sample doesn't work as I would expect? The only thing I can think of is that the RegEx pointer isn't being preserved on each iteration, but I don't understand why....

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