Errata

"perl -Mre=debug explain_regex" should be
"perl -Mre=debug explain_regex.pl" to match previous examples.on page 25.

As per previous paragraph ("and using the full path to echo"), "echo" should be qualified with the full path, like "/bin/echo".

Strangely, the example still works, even with PATH unset, probably because it is using the shell's builtin echo, or perhaps because even with PATH unset, perl's "system" function seems able to find things in /bin.

The 1st and 2nd example invocations of "perl glob_opendir.pl" on the page are correct, but the 3rd example, directly after the 2nd, runs "perl big_dir.pl", a perl program which is not defined anywhere in this chapter. It appears that it should instead be yet another "perl glob_opendir.pl", as the example is to show that repeating the same command results in differing (timing) output.

Top of the page:

use v5.10;
$foo = "Some value";
$bar = "Another value";
who_am_i( *foo );
who_am_i( *bar );

sub who_am_i {
local *glob = shift;
say "I'm from package " . *glob{PACKAGE};
say "My name is " . *glob{NAME};
}

The output when running the above is:

I'm from package main
My name is glob
I'm from package main
My name is glob

Compare with the book (page 141):

I'm from package main
My name is foo
I'm from package main
My name is bar

To me, it seems like *glob{NAME} is not copied along when aliasing in the who_am_i() sub (local *glob = shift). I am using perl version 5.22.1. Was this supposed to work on earlier perl's?

<C: set DEBUG=2 # Windows>>
should be
C:\>set DEBUG=2 # Windows

/bin/sh and bash shells will require "export" before each of the environment variable names, otherwise the called "./program" will never see the values you are trying to set, as they remain local vars to the shell, not env vars. As is, the code does not work as intended.

If the final else { last; } executes, the print $fh at the very bottom of the code will try to print on an unopened file handle. The print needs to confirm first $fh was opened successfully somehow. Same applies to the "last if $try++ >= 2" test from page 209.

This doesn't mean, however, the the programmer has ...

two "the"

'line' -> __LINE__ - 1,

will have to be changed to __LINE__ + 6 if you want to what is says is desired in paragraph 2: have the line be the line of the die. Probably when first writing this code the author die'd directly on the Hash::AsObject->new line instead of creating an intermediate temp var $error.

Also, Data::Dumper is not used anywhere in that code example and its use line can be deleted.

First, the second line of the program is
#bal_call.pl
, but it's run as
%perl bad_call.pl
The online sample code (which, like the rest, is in a directory named +1 of the actual chapter) is in a file named bal_call.pl

Second, the output shown is wrong:
It should be
I'm die-ing in badcall! at bal_call.pl line 6.
( "...or bad_call.pl ...")

You are setting the ISBN in the code to 0596527241 but in the sample output it is 144939311X

if ( ref $isbns ) {

should be

if ( !ref $isbns ) {

The last part of the "In HTML" line needs a slash before the final i to be valid HTML, like:

PerlE<lt>/iE<gt> to

Probably markup formatter typos:

<% perldoc CGI cgi.txt>>

should be

% perldoc CGI >cgi.txt

Also, once again the bold is disabled before the end of the example line.

Result is invalid, should be: 1010. The mask was probably intended to be different, as it's a bad example of masking since no bits in the first operand would be masked out, thus rendering the example somewhat pointless.

my $class = $classes[ $row++ % ($#class + 1) ];

should be

my $class = $classes[ $row++ % ($#$classes + 1) ];

$self->STORE( $list_ref ) ) {

should have just one closing paren. As is it's a syntax error.

The call to carp has two strings, which must be joined with a dot. As is, it's a syntax error.