Intermediate Perl Book

A useful but ultimately frustrating book, too difficult for me I think. It's certainly NOT recommended to read this after Learning Perl , without doing a decent amount of practical stuff first.

Because it was too hard for me, it's fair enough to say (and I won't contest it) that I'm just grumpy because something made me feel stupid. But I think there were several things that were not done well in this book. One consistent thing was that it was hard to understand the exercises: what is it that they want me to do exactly. This lead into misunderstanding the task at hand and the resulting waste of time and frustration. It really is easier to have your own tasks with which to practise, because then you know what you want to accomplish, which is the opposite of trying to understand someone else's ideas about what needs doing. So IMO better to skip the exercises and practise by writing your own scripts for your own tasks. It's another matter of course whether you can come up with useful examples where you need the stuff that they taught you in the last chapter etc.

They've calibrated the estimated times for this or that exercise up by quite a bit compared to Learning Perl. Frankly it's a lot better doing exercises that are said to take around 25 or 40 minutes, rather than the 5 or 7 minutes or something which was more the norm in LP. That was just depressing and made me feel like Gomer Pyle (in Full Metal Jacket). But also on another level the exercises in this book felt like a replay of the exercises from LP: for example, I didn't even understand the question in Chapter 4 exercise one.


"How many different things do these expressions refer to?

$ginger->[2][1]
${ginger[2]}[1]
$ginger->[2]->[1]
${$ginger->[2]}[1]"


"How many different things"?? Like, how many things does the first expression refer to, and how many things does the second one refer to, etc.? It seemed like $ginger refers to an array whose name is not known, its third element, which in itself is an array, and that array's second element. But what do you mean, "how many different things"? One?? Turns out the question was, "Do each of these four lines refer to the same thing, or do each of them refer to a different thing, or some to the same thing and some to different ones?" Seems like this trio really should have worked on their wording a bit more.

The answers in the back of the book mostly made sense of course when I read them (though often I just didn't bother), but I really think they should have made simpler exercises to start with. Each chapter had just two or three exercises, whereas I think the proper number should have been around 8-10. Then you could have started with simpler exercises that controlled that the student had understood the basics, and only then make the exercises progressively more challenging. Now already exercise 2 was the kind of "additional tasks for advanced students" type that math classes in school used to have. The way they were here just killed my motivation to even try, because even though I e.g. understood the reference concept (not really thanks to this book I might add), the bar was just set too high already in the first few exercises for the chapter. So I just skipped the exercises.

The presentation of the new stuff in each chapter could have been a lot better. Partly they did this ok, but partly not. The parts where they don't do it are quite dense (grep inside grep, map inside map etc.), and it's hard to be sure that you really understood it, because I don't think they were helping me much.

Other gripes include:

Chapters 4 and 5 mix the use of "$ref_to_skipper" and "$reference_to_skipper" in the examples, even though apparently they're supposed to be the same thing. Calling it consistently "$ref_to_skipper" would have been better, in fact the only justifiable choice, there was enough going on to confuse you without this kind of nonsense.

Chapter 4, second exercise: "Using the final version of CHECK_REQUIRED_ITEMS, write a subroutine..." Why not give the page to the "final version"??

Chapters 4 and 5 (p. 44, 55) use the following notation:

my @skipper = qw(blue_shirt hat jacket preserver sunscreen);
my @skipper_with_name = ('Skipper' => \@skipper);

A fat arrow in an array??? (Also in Ch.6, p. 89). Maybe I missed the section where they explained it, but why didn't they just use a normal comma, which is (more or less) the same as a fat arrow? I was used to having fat arrows only in hashes, and lists in arrays I have seen were written with commas (or with qw() or whatever), so this confused me completely. Whether or not they explained it somewhere, it was a really bad call to confuse the already complicated topic of Perl references with "alternative" notation without explaining it in the context they used it. Later in Chapter 5 (p. 59) they do use the comma version of the same example, without any explanation as to why they changed the notation (@skipper_with_name = ('The Skipper', \@skipper);).

Why?? If they wanted to say that "there's more than one way to do it", they should have said it out loud, rather than implied it. This is supposed to be a study book FFS.

I didn't like how they introduced modules here and there to be used in a few examples (Data::Dumper is an exception). I'm sure they're useful, but I would have preferred that they have their own section or something. Random modules got in the way of understanding first the basic logic of the new things being taught, and it would have been better to get through the "vanilla Perl" stuff first, and then introduce some useful modules or whatever, in a wholly separate section. Now they were just clogging up the already quite dense text with more moving parts.

As a self-study book for someone who already doesn't have a firm grip on Perl, I don't recommend it, certainly not right after reading LP. I stopped reading after Chapter 7, I think I'll need at least 6 months of weekly practical Perl writing before it makes sense to continue. And as I'm just writing scripts for my own personal use and don't see my needs going further than that at the moment, it's entirely possible I won't ever have the need to read anything beyond say Chapter 10. Had I known this I think I wouldn't have bought the book.