Re: Perl: friend or foe ?

Also of interest to me is whether the fact that its not precompiled could affect its performance, again with reference to other languages. Would it be better to compile the code first so that each time it is run it doesn't have to be interpreted each time.

That's two separate questions. First, let me clearify something. Perl code is compiled before it's run. The Perl code itself is never "interpreted each time" as with, for instance, shell code. Perl code is compiled when you start the program, and then the resulting code is run.

As for whether it impacts performance, yes, in some ways. Both negatively, and positively. Let me list some cons first:

Because Perl code is compiled each time the program is run, compilation needs to be fast. Perl can't spend a lot of time optimizing the resulting byte code, sometimes resulting in code that might not be as fast as it could have been.
If you run the same, unmodified, code many times, over and over compiling the same thing can be percieved as "wasteful".

The pros:

Perl source code takes much less disk space than any compiled code, so by doing "just in time" compiling, one saves disk space.
There's no risk of having the source code and the binary code be out of sync, as there's no separate binary around.
No need to generate binaries for different platforms. Most code I write on my OS will run on your OS without even knowing what your OS is.
A much shorter write/test cycle - no separate compilation cycle needed.

In short, whether or not it's "better" to compile the code first is a matter of preference - you win some, but you lose some as well. It's a trade-off, and for now, it means you'll have to live with "just in time" compiling.

In Perl6, you probably will have the option to save the byte code after compilation.

Comment on Re: Perl: friend or foe ?

Replies are listed 'Best First'.
Re: Perl: friend or foe ? by MonkPaul (Friar) on Apr 25, 2005 at 20:04 UTC
Monkers, I think everybody had their say on that one. I was'nt trying to kick up a fuss but merely answer some of my own questions by asking you lot. Cheers :) Two more question's ........ If Perl is so neat and nifty for the things its used for, why does it never get taught at a lower level? Im doing a masters and only just heard about it after christmas. I would like to see a choice of what languages you can learn when you begin you programming course. Is this the same for everybody?	[reply]
Re^2: Perl: friend or foe ? by merlyn (Sage) on Apr 25, 2005 at 23:00 UTC
Perl certainly wasn't around when I started learning programming. Heck, Larry Wall wasn't even programming then. {grin} I spent the first six or seven years learning (and later teaching) BASIC. Then I discovered C, and Pascal, and FORTH, and Logo, and realized how much larger the world must be. -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply]
Re^3: Perl: friend or foe ? by softworkz (Monk) on Apr 26, 2005 at 19:40 UTC
Perl IS neat and nifty for just about anything! FYI Perl is taught at the "lower levels", I myself took Perl my second year, maybe you should change schools? I wish it was around when I was in High School, but as Merlyn points out Perl wasn't around yet. shudders at BASIC =:-)	[reply]
Re^2: Perl: friend or foe ? by willyyam (Priest) on May 02, 2005 at 14:08 UTC
Perl is not necessarily going to be attractive as a pedagogical language - partly because of TIMTOWDI. Also, there have been criticisms that Perl code is auto-obfuscated, which makes evaluation on pedagogical grounds challenging. In my (limited) experience, Perl is used to get things done, and teaching languages are used for teaching. Perl exposure in academia is more likely to happen in the experimental sciences or occasionally in the Arts. If you are interfacing with telescopes, gathering data from sensor arrays or modelling bioinformatic systems, you'll likely hear about Perl before it would come up in CS.	[reply]
Re^2: Perl: friend or foe ? by Anonymous Monk on May 03, 2005 at 08:19 UTC
If Perl is so neat and nifty for the things its used for, why does it never get taught at a lower level? For the same reason they don't teach quantum physics at a lower level. Nor do you get to use a 747 to get your pilot license. And your grandfather didn't take you out to sea for some shark fishing the day got your first fishing gear. Perl is a powerful language, but only in the hands of a skilled and experienced programmer. And then only some of them. Im doing a masters and only just heard about it after christmas. I would like to see a choice of what languages you can learn when you begin you programming course. You're doing a masters in what? Computer Science? Well, that's a lot, a whole lot, more than programming. And if you don't like what you get at your university, talk to them, or find a different university.	[reply]
Re: Perl: friend or foe ? by MonkPaul (Friar) on May 05, 2005 at 13:52 UTC
Im doing a masters in Bioinformatics. My undergrad was computing and biology. Im not talking about what im doing here. What i said was "I only just heard about it after christmas", which is partly the fault of this uni, but also of all other uni's. None of them offer perl courses or teach perl programming.	[reply]
Re^3: Perl: friend or foe ? by Willworker (Acolyte) on May 03, 2005 at 21:38 UTC
For the same reason they don't teach quantum physics at a lower level. Nor do you get to use a 747 to get your pilot license. And your grandfather didn't take you out to sea for some shark fishing the day got your first fishing gear. Perl is a powerful language, but only in the hands of a skilled and experienced programmer. And then only some of them. I don't know-- I'd probably not count myself a "skilled and experienced programmer." I've taken a few classes in college, but I got turned on to perl in my work as a sysadmin-hobbyist. None of the tasks I wanted to automate were difficult; they were usually minor text transformation and redirection. Perl was great because it /was/ simple. As the camel book says, "Perl is designed to make the easy jobs easy, without making the hard jobs impossible." For teaching simple programming, perl's great-- you don't need all the magic incantations (class HelloWorld { public static void main(String[] args) { System.out.println("Hello, world!");}}) or strange operators (cout << "Hello, world") of other languages. You don't need to fight to teach about data structures (perl arrays are arrays, queues, stacks, and so forth), since they're just /there/ and working. And then there's passing by reference vs. value, which perl largely dwims away. If you want to introduce functional programming as compared to imperative programming, perl lets you do that, too. For basic programming, I'd probably start with perl instead of Java or other similar languages. There's certainly value in teaching C++, especially when you want to start talking about lower level computer guts, but basic programming doesn't generally need/want to talk about memory allocation and other complex problems. Steve	[reply]