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Perl 6 Now by Scott Walters
Joseph Brenner writes "Every now and then, a beginning programmer asks if there's
any point in learning to program in Perl 5, when Perl 6 is
going to change everything soon. There are a number of
answers to that: one is to point out that Perl 6 is still
years away, another is to point out that it is promised that
Perl 5 code will run under Perl 6 without modification (a
module that begins with the traditional "package" statement
is Perl 5 code; if it begins with the new "class," then it's
Perl 6)." Read on for the rest of Brenner's review of Scott Walters' Programming in Perl 6 style using Perl 5, a book which answers that question a whole different way.
Perl 6 Now
author
Scott Walters
pages
379
publisher
Apress
rating
7
reviewer
Joseph Brenner
ISBN
1590593952
summary
Programming in Perl 6 style using Perl 5
Scott Walters here pursues what might be thought of as the third answer: you can learn Perl 6 now and immediately begin writing programs in a "Perl6ish" sort of way, using appropriate CPAN modules that have been used to implement approximations of Perl 6 behavior: Perl6::Variables, Perl6::Export, Perl6::Contexts, autobox, Perl6::Classes, Switch, and so on.
There are many caveats about using these tricks in production code, however, and Scott Walters doesn't shy away from warning you about them (e.g. p.43 "Source filters are dangerous" where he discusses their increased start-up overhead and potential bugginess -- though he doesn't mention my own peeve which is that they're very confusing when you try and use the Perl debugger).
So possibly the book is not really quite so well suited to an actual beginner-- who probably should not be told about "use Switch 'Perl6'", but the device of spending the early stages of the book directed toward a beginning audience makes it a very useful review for people like myself who have been reading the Apocalypses, but don't remember every detail.
And on the other hand, the book includes some prominent early warnings about common gotchas that beginning programmers seem to be prone to -- e.g. using dynamically defined variables instead of just using hashes.
The standards for writing English in the Perl world are pretty high -- the core members of the Perl community have always cared a lot about clear writing, and it's arguably the world's best documented language (critics will no doubt add that it needs to be). Unfortunately, I can't say that Perl 6 Now quite lives up to this standard. This is a book that was written in a hurry, and it shows: hasty sentences and minor organizational problems abound (e.g. one or two items seem to be discussed in the wrong place; there are an awful lot of explicit forward references, and yet there's at least one place where something was used in an example before being discussed a few dozen pages later). But then in Scott Walters defense, this is certainly a book that needed to be written in a hurry, because its subject matter is such a moving target.
And where the book really shines is in its code examples: short, clear and to the point; the author repeatedly shows how something can be done in Perl 5 code and how it's expected to work in Perl 6. These examples are always clearly labeled "Perl 5" or "Perl 6" in the comments, so that the two can't be confused.
The subjects of some of the examples are pretty cool: e.g. he talks about using PDL ("Perl Data Language") to crunch audio data in MOD format, which I was completely unfamiliar with. A *.mod file essentially contains the "sheet music" for multiple parts (really, MIDI) plus sound samples that specify how notes will sound for each voice. This is discussed in Chapter 7, which is also the free sample chapter. I also liked random walking Arizona's highways as an example of Graph navigation (Chapter 8, p 159), and I appreciate the fact that he downplays inheritance in favor of delegation in his discussion of objects (Chapter 14, p. 262).
All in all, this book is a fun read for the Perl fanatic.
(Note: the title Perl 6 Now bears a strong resemblance to an emacs package I've been working on called perlnow.el, but there is no relation.)
You can purchase Programming in Perl 6 style using Perl 5 from bn.com; it's also available in eBook format (password protected PDF, using your email as password) for $15. Source code and and a sample chapter are available online: Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
Scott Walters here pursues what might be thought of as the third answer: you can learn Perl 6 now and immediately begin writing programs in a "Perl6ish" sort of way, using appropriate CPAN modules that have been used to implement approximations of Perl 6 behavior: Perl6::Variables, Perl6::Export, Perl6::Contexts, autobox, Perl6::Classes, Switch, and so on.
There are many caveats about using these tricks in production code, however, and Scott Walters doesn't shy away from warning you about them (e.g. p.43 "Source filters are dangerous" where he discusses their increased start-up overhead and potential bugginess -- though he doesn't mention my own peeve which is that they're very confusing when you try and use the Perl debugger).
So possibly the book is not really quite so well suited to an actual beginner-- who probably should not be told about "use Switch 'Perl6'", but the device of spending the early stages of the book directed toward a beginning audience makes it a very useful review for people like myself who have been reading the Apocalypses, but don't remember every detail.
And on the other hand, the book includes some prominent early warnings about common gotchas that beginning programmers seem to be prone to -- e.g. using dynamically defined variables instead of just using hashes.
The standards for writing English in the Perl world are pretty high -- the core members of the Perl community have always cared a lot about clear writing, and it's arguably the world's best documented language (critics will no doubt add that it needs to be). Unfortunately, I can't say that Perl 6 Now quite lives up to this standard. This is a book that was written in a hurry, and it shows: hasty sentences and minor organizational problems abound (e.g. one or two items seem to be discussed in the wrong place; there are an awful lot of explicit forward references, and yet there's at least one place where something was used in an example before being discussed a few dozen pages later). But then in Scott Walters defense, this is certainly a book that needed to be written in a hurry, because its subject matter is such a moving target.
And where the book really shines is in its code examples: short, clear and to the point; the author repeatedly shows how something can be done in Perl 5 code and how it's expected to work in Perl 6. These examples are always clearly labeled "Perl 5" or "Perl 6" in the comments, so that the two can't be confused.
The subjects of some of the examples are pretty cool: e.g. he talks about using PDL ("Perl Data Language") to crunch audio data in MOD format, which I was completely unfamiliar with. A *.mod file essentially contains the "sheet music" for multiple parts (really, MIDI) plus sound samples that specify how notes will sound for each voice. This is discussed in Chapter 7, which is also the free sample chapter. I also liked random walking Arizona's highways as an example of Graph navigation (Chapter 8, p 159), and I appreciate the fact that he downplays inheritance in favor of delegation in his discussion of objects (Chapter 14, p. 262).
All in all, this book is a fun read for the Perl fanatic.
(Note: the title Perl 6 Now bears a strong resemblance to an emacs package I've been working on called perlnow.el, but there is no relation.)
You can purchase Programming in Perl 6 style using Perl 5 from bn.com; it's also available in eBook format (password protected PDF, using your email as password) for $15. Source code and and a sample chapter are available online: Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
I hate to be Jonny Raincloud, but pretty soon PHP will be able to do whatever perl does, if it's not there already. And anything that it can't do that perl can will be obsolete. So no, don't waste your time learning perl 6. Do the right thing and brush up on your PHP5. I got my site to print in any font I want the time AND date, powered by php, baby!
The standards for writing English in the Perl world are pretty high -- the core members of the Perl community have always cared a lot about clear writing
Yeah, right. Why should one obfuscate English, Perl offers much more possibilities to do so.
I believe that CPAN is one of the major (if not the only) things keeping Perl alive and well.
It is a great language, and has been used successfully by many huge companies (Amazon for one), but I think if those companies had to redo it again today, I don't think they would choose Perl again. I think that purely as a language, it has been surpassed.
Having a large, mature 3rd party library is what is hampering the adoption of some of the up and coming languages.
Where are the Ruby on Rails people? I expected 100 of them to speak up before the traditional "FRIST PSOT!!!"
Well, for one, perl now has a nice framework similar to Rails called Catalyst (http://catalyst.perl.org/). It's a lot closer to Rails than a lot of other languages' attempts to clone Rails. And yet the Catalyst dev team have specifically chosen to diverge from Rails in certain areas, trading a bit of simplicity for complete flexibility, avoiding some limitations you could run into in Rails.
bp
I was going to bring this up in the thread about beginning programming the other day, but I came too late to the party. Hopefully someone can offer me some advice.
First, I'm not really a programmer. Not professionally, at least. I've been writing Perl for about four or five years, though. I'm not well-versed in OO and I'd like to be. I've just found it such a stumbling block in Perl and that's probably because I'm doing in Perl in the first place. It's the first language I picked up since I played around with BASIC and Pascal as a little kid.
I run a large auction site. Maybe 40,000 members. I wrote the entire engine (auction, forums - everything) in Perl. But it's getting complex and difficult to maintain as it is. And the performance is not holding up. I could move to mod_perl, but rather than re-writing everything (and possibly doing so in OO), I thought I'd just write it in another language.
I don't want PHP. So that leaves me mostly with Python and Ruby. I've done a lot of reading, but am not sure which would be more appropriate. I think Python might stick me back in the old "easy to do things wrong and blow your foot off" world of Perl. Ruby on the other hand would probably help me gain a better understanding and real-world use of OO.
Performance is an issue. So are available packages. My backend is postgresql and I need whatever language I use to have an extremely capable and flexible and mature postgresql DBI.
At the moment, I have to say I'm leaning toward Ruby. But it does seem that Python might have more mature packages available to it and be a bit more widely used. I'm just skittish because everything I've heard has given me the impression that it's very Perl-ish and if I'm going to be in that world, I might as well just stick with Perl in the first place.
Thoughts?
Everyone attacks Perl code for being unreadable but I don't think I've ever come across real world Perl code that I couldn't manage to deal with (eventually). I've seen some bad code and written some bad code and Perl doesn't have exclusivity in either of those areas. ;)
Does someone have a good example of unreadable, real world Perl code? And I don't mean obfuscated Perl contest entries.
When it comes down to it, other people's code is just freakin' unreadable no matter what they write it in. In fact, my own code looks unreadable and unmanagable if I haven't seen it in awhile. Just the nature of the industry.
Maybe Perl is just a high profile target since the internet is full of small (and useful) pieces of Perl code?
Please do not moderate parent up, because it's just a guess at most.
Perl6 is actually built from user feedback, for the first time.
From wikipedia: Larry Wall, the creator of Perl, has called Perl 6 "the community's rewrite of Perl", because he has based the changes largely on 361 "requests for comments" submitted by the Perl community in 2000. He is outlining these changes in a series of long essays, called Apocalypses, which are numbered to correspond to chapters in Programming Perl ("The Camel Book"). The current, unfinalized, specification of Perl 6 is encapsulated in design documents called Synopses, which are numbered to correspond to Apocalyses.
Parent is NOT insightful.
It takes a man to suffer ignorance and smile
Be yourself no matter what they say
Perl6 has the advantage of starting from the beginning, taking all that was learned from the evolutionary development that lead to Perl5, as well as the lessons learned from other languages like Python and Ruby. Honestly, read through the design commentary for Perl6 by Larry Wall. There are a lot of good ideas there, and Perl6 promises to be a much cleaner, more consistent and more elegnt language than Perl5 - that is, it has learned what was good in Perl5 and thrown away the (vast amounts) of cruft. Looking at what they're proposing, if it actually works as promised then I do think it will compete well with Python - and I'm a Python person myself*. Honestly, read a little of what Perl6 has to offer before you dismiss it out of hand. It looks like it will be a very nice language indeed.
Jedidiah.
* One of the things I like about Python is that they're willing to deprecate and then *remove* features to help combat cruft.
Craft Beer Programming T-shirts
The same goes for Java.
Bash and Awk are not powerful enough to do some of the jobs Perl can do. And Perl is only slow with some things, and in comparison to really serious languages like C/C++.
check out "http://pugscode.org/"
_ p6.html
for a working perl6 compiler. Yeah, it is not yet feature complete, but progress is very rapid.
Perl6 is really amazing. It removes most of the worst parts of perl5 and make things even easier on the programmer. If you do an research at all you can find that.
Some people are even starting to port important CPAN modules to perl6 and discovering how much a pleasure it is to use.
see http://www.perl.com/pub/a/2005/07/28/test_builder
as an example of that.
btw, check out the example code. for all of you who think perl5 looks like static on a tv screen, you will be pleasantly surprised I think.
peace
Peace, or Not?
Ruby on Rails blows away Perl. I used to code in Perl, but I was working on re-implementing Windows XP as a Firefox extension, and I just wasn't getting the productivity that I wanted out of Perl.
So I switched to Ruby on Rails this morning, and I'm so productive, that its sick. Within 5 hours, I have a Firefox extension running on my AIX workstation that can run most Win32 software... Photoshop, Outlook and Half Life 2 work ok, although I only get 40fps with HL2. (I'm working on that)
After dinner I'm going to reproduce every module in the CPAN library, which I estimate will take approximately 2.25 hours. I can't wait!
Conformity is the jailer of freedom and enemy of growth. -JFK
I stopped using Perl over ten years ago, when I had a disagreement with Tom Christiansen and he seriously threatened to blacklist me from the Perl community if I didn't agree with him. I told him to go ahead, because I would simply never write Perl again. He laughed and told me to let him know how that went.
Well, it went just fine. I haven't written a single line of Perl since that day, and I haven't missed it one bit.
These days, with so many options available, I think Perl appeals to a certain kind of developer in much the same way Java does. You don't really NEED it, in the sense that many other things can do the same job... but it's a point of style. Java and Perl now serve primarily as focal points for very small and specific communities that otherwise wouldn't really exist in a coherent fashion, much like APL or Objective-C. Ruby is similar, and I don't really see it going mainstream. These sorts of niche technologies still do the job, and selecting one of them instead of a more "mainstream" language like PHP or C++ identifies you as a particular kind of person.
Microsoft cheerleader, blue flag waving, you got a problem with that?
Every time you post a message to this website, you're using Perl. You'd better stop before you foolish irresponsible behavior catches up with you.
I've been asking myself a lot lately why so many people seem to hate Perl. After spending the last few years going from comfortably familiar to extremely familiar with the syntax and features, I think I have the answer.
When you really get down into the guts of perl, you get to do all kinds of crazy nifty things with XS, AUTOLOAD, regular expressions, etc. Perl's syntax is such that once you're intimately familiar with it, you can be either very expressive or very concise.
A lot of code ends up going the concise route because when you know what you're doing, it's easier to write (less keystrokes). Then perl newbies / passer-byers take a look at it, don't understand it, and freak out and say that perl is crap.
Then perhaps they're threatened because there's a huge community of smart perl programmers that manage to upstage them constantly.
To zoom out on the issue a bit, I'm really sick and tired of this current movement in computer science where so many think that programming should be made into some kind of simple task that anyone can do. Hence you end up with languages like Java that hold your hand really really tight and refuse to let go. Is Grandma writing software really a good thing? Or should we save it for the people who at least have a passing familiarity with computers & networks; hell, someone who might even know a little bit about the basic mechanisms in a typical UNIX kernel?
(I refuse to drive a car built out of legos... I don't care that the technology enabled your three year old to do it... it's a high speed highway, damnit, and my life is on the line!)
Make no mistake - there's still an undergound of brilliant developers that understand their systems inside out and produce amazing, high performance code. Many of them are in the open source community. And we refuse to let go of our power tools. You may use whatever language you like, but expect a well-deserved ass kicking if you get in our face and try to tell us you know better.
never using a programming language again due to an argument you had on the internet identifies you as a particular kind of person.
I prefer programming in Perl to Python. This is primarily because Perl has better variable scoping, which combines nicely with "use strict" and "use warnings FATAL => 'all'".
In Python, there are two scopes for variables: Global and Function. In perl, any { block } gets it's own scope for "my" variables. This means that temporary variables disappear when you're done with them rather than sticking around clogging up memory and name spaces. Because perl has variable declaration statements (my, our), it can check at compile time to make sure you have no typos in variable names. In python, any time you do an assignment you might be declaring a new variable - and you'll never know until you get incorrect output.
Also, Python has no do...while(). This gives you the amazing choice of duplicating program logic (awesome when you change only one instance later) or putting in a "while 1:" - rather than knowing where the loop condition is, the maintnence programmer gets to randomly guess *and* this opens the way for "sometimes the loop never ends" bugs. Not good times.
I'm looking forward to Perl 6 where it will be possible to have semi-static typing. That will mean even less code that compiles but doesn't work. I really wouldn't want to be using a language without similar features for any sort of non-trivial software project.
-- The act of censorship is always worse than whatever is being censored. Always.