Monthly Archives: May 2008

The oxymoron of perl best practices

I’ve been browsing Damien Conway’s excellent book, Perl Best Practices. His description of “best practices” in Chapter 1 is quite good, bestowing meaning upon an otherwise empty buzzword for marketing departments:

Rules, conventions, standards, and practices help programmers communicate and coordinate with one another. They provide a uniform and predictable framework for thinking about problems, and a common language for expressing solutions. This is especially critical in Perl, where the language itself is deliberately designed to offer many ways to accomplish the same task, and consequently supports many incompatible dialects in which to express any solution.

Simply put, best practices are the recognizably tried-and-true. The key word is recognizable: others should be able to identify the problem being solved as well as the specific type of solution. In a way, it’s redundant to speak of best practices when talking about the programming: unless no one will ever see your code, the foremost consideration of the programmer should be, Can other people understand what I’ve done easily and quickly, and also make changes and improvements easily and quickly?

That question is really at the heart of coding as a craft of logical elegance, I feel. Giving it due care and consideration is what distinguishes artisans from those who just “get it done” (they always seem to run into perpetual headaches down the line).

I find the philosophy of perl to be highly antithetical to the sort of shared understanding and communication described above. The motto of “there’s more than one way to do it” is self-serving and individualistic, to the detriment of maintainability. Perl seems to foster stubbornness and isolation: I’ll do things MY preferred way, and you do it YOURS. The codebase quickly devolves into baffling inconsistency. Of course, skilled perl programmers pride themselves on being able to know all the different ways of doing something, but at that point, the strength of the language isn’t the issue anymore; the ego of the coder is.

Anyway, back to Conway’s book. What’s interesting, but perhaps not surprising, is the number of “don’t do X” recommendations it makes. Leaving off parentheses on subroutine calls? Convenient, but ugly and confusing when a bunch are these are combined, so don’t do it. Tricks with dereferencing syntax? Save everyone headaches and stick to arrows. Pseudohashes? Stay away from them. Indirect object syntax? Potentially conflicts with subroutine names, so don’t use it.

Take away all the crazy tricks that perl devotees love, and what’s left? The only truly great thing about perl is its regular expression integration and text processing. It’s amazing stuff. But otherwise, perl doesn’t particularly excel at much else.

Which is not to say large complex projects in perl are impossible. The University of Washington’s Catalyst tools use a custom web framework written in perl, which they’ve open sourced. I only cite that particular example because I’ve used some of the tools and I know they’re nicely done. So sure, it’s possible, but it takes a lot of deliberate restraint and discipline, more so than with other languages and tools that are oriented towards helping you get your job done.

Seems to me that if you must willfully refrain from using what a language offers, and constantly fight the temptation to write mangled code that costs time, money, and frustration for others to decipher, perl isn’t a particularly strong choice. In the case of perl, best practices aren’t a way to get the most out of the language; they’re a stopgap measure to stave off its natural tendency towards chaos.

Eclipse and JDK 1.6.0_05 on Mac OS

Last week, Java 1.6 went out of Developer Preview and became an “official” release for Mac OS 10.5.2. (You still can’t get 1.6 for 10.5.1, sadly.) I’ve been fiddling with 1.6 and Eclipse, trying to get them to play well together, and here’s what I’ve found so far.

Eclipse itself needs to run on 1.5. There’s a great blog post, “Running Eclipse on MacBooks with Java 6”, written by one “rkischuk,” that explains why: 1.6 doesn’t support 32-bit SWT-Cocoa bindings, so Eclipse will bomb. The error I got was a mysterious “JVM Terminated. Exit code=-1” and a list of run-time options. If you run Eclipse from a shell, you might see this:

2008-05-09 10:53:55.443 eclipse[257:10b] Cannot find executable for CFBundle 0x116030 (not loaded)

or maybe this:

_NSJVMLoadLibrary: NSAddLibrary failed for /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Libraries/libjvm.dylib
JavaVM FATAL: Failed to load the jvm library.

When I installed 1.6, I had messed around with /System/Library/Frameworks/JavaVM.framework/Versions, trying to get 1.6 to run as the system default. But the cleanest solution for me was to KEEP 1.5 as the default. So make sure that directory looks like this:

drwxr-xr-x 11 root wheel 374 May 9 10:49 ..
lrwxr-xr-x 1 root wheel 5 May 5 22:41 1.3 -> 1.3.1
drwxr-xr-x 3 root wheel 102 Nov 2 2007 1.3.1
lrwxr-xr-x 1 root wheel 5 Apr 18 13:07 1.4 -> 1.4.2
lrwxr-xr-x 1 root wheel 3 May 5 22:41 1.4.1 -> 1.4
drwxr-xr-x 8 root wheel 272 Apr 27 2007 1.4.2
lrwxr-xr-x 1 root wheel 5 Apr 18 13:07 1.5 -> 1.5.0
drwxr-xr-x 8 root wheel 272 Apr 27 2007 1.5.0
lrwxr-xr-x 1 root wheel 5 May 5 22:41 1.6 -> 1.6.0
drwxr-xr-x 8 root wheel 272 Apr 18 14:03 1.6.0
drwxr-xr-x 9 root wheel 306 May 9 10:50 A
lrwxr-xr-x 1 root wheel 1 May 9 11:13 Current -> A
lrwxr-xr-x 1 root wheel 3 May 9 11:12 CurrentJDK -> 1.5

Eclipse should run as it normally does.

If your code project(s) don’t require SWT, you can use 1.6 as an Installed JRE within Eclipse. Go to Preferences -> Java -> Installed JREs -> Add…. Select “Mac OS VM” and point it to:

/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home

Building projects and running JBoss using the 1.6 seems to work just fine.