ActiveState Perl Debugger Gets the Bugs Out

ENT, Sept 10, 1998 by Michael Bender

Although the roots of Perl stem from Unix, the programming language designed for processing text has been ported to a variety of platforms, including AS/400, Macintosh, MS-DOS, Novell NetWare, Windows 3.1, Windows 95 and Windows NT. And with the increase in Windows NT Web servers, Perl is becoming a popular choice for designing Common Gateway Interface (CGI) programs on Windows platforms.

Because Perl is a noncompiled language, Perl scripts run on multiple platforms with minor modification. This offers developers a large free script base and many built in modules, as well as the ability to develop and debug on one platform and deploy on another. To help developers debug Perl programs, ActiveState Tool Corp. released the Perl Debugger for Windows 95 and Windows NT.

We tested the ActiveState Perl Debugger on a 300-MHz Pentium II with 64 MB of RAM, running dual-boot Windows 95 osr2 and Windows NT 4.0 Workstation Service Pack 3. The ActiveState debugger requires a Pentium 90 or faster, 16 MB of RAM, 2 MB of disk space, and Windows 95 or Windows NT 4.0. Perl for Win32 build 310 or later is also required. To check which version of Perl you are running, type perl -v at the command line. The latest version is available from the ActiveState Web site.

To start debugging perl scripts, we executed a Perl program from the command line using the -d option, typed as follows: perl -d myprogram.pl. A Windows screen appeared with Source, Watch, Proximity and Register windows filling the screen.

The source window enabled us to see our lines of code and follow our program's progress by using the Instruction Pointer. The code is numbered by line and color-coded for easier reading. In the Watch windows we found the first device for viewing variable values. Adding a variable to the window was a cinch, and the variables are updated as each line of the program runs. In the Proximity window the values of variables are displayed. Customizing the options in each of these windows for our own personal preferences was a snap.

To step through a program, the ActiveState Perl debugger has four options. They are curly brace buttons named Step Into, Step Out, Step Over and Run to Cursor. With these buttons we got the debugger to run the program line by line, jump to the end of a subroutine, skip a line, and run to the Current Line Pointer.

A user can insert breakpoints by right-clicking on the Source window. A breakpoint is a spot where the program can be stopped to analyze a variable or made to stop only on a condition. We used a series of breakpoints and the Continue button, and we found this to be an effective means of debugging a program.

Another aspect we found helpful was the edit command found in the tools menu. ActiveState claims that by utilizing this feature, any word processor can be edited. We could easily set the editor of choice by using the customize menu item.

On the whole we found this application simple to use. It is straightforward in design and operation, and can be customized easily. The bottom line is that Perl Debugger is a debugging product, and it gets the bugs out.

Perl Debugger Version 1.0 Build 17

ActiveState Tool Corp.

Vancouver, British Columbia

(604) 606-4686 www.activestate.com

Price: $95.

Easy to use.

Advanced functionality.

- Needs more development features.