Updated 2016-10-31 19:09:56 by SEH

Debugging is the of process diagnosing and correcting unexpected behaviour of programs.

Description  edit

There are many debugging techniques, ranging from simple puts commands added appropriately to visually oriented tools supporting breakpoints, etc.

Use of a virtualization environment such as VMware, or the free alternative, VirtualBox, allow one to set up an entire environment - perhaps even unique operating system - then perform testing with less impact on the machine itself.

If you are testing across various platforms, you might find Virtual Network Computing (VNC) (also known as remote control) helpful software, as it allows you to connect to other computers and interact with them as if you were sitting with with that software installed on your desktop.

See Also  edit

Category Debugging
IDE
many of which provide debugging functionality along with other features
Profiling Tcl
Static syntax analysis
Tools for the analysis of source code.

Concepts  edit

call graph

Tools for Dynamic Analysis  edit

a basic debugger
a debugger with syntax highlighting using ctext
A minimal debugger
atkdebugger
A patch for Tcl 8.5 is available at the website
d: A handy little debugging proc
by Ed Suominen, for development of PRIVARIA [1], an end-user TCL app with a lot going on inside.
a minimal debugger
implements breakpoints, allowing to run any Tcl command, including inspecting and setting the local variables...
Errx
a mixed debug-message / stack backtrace introspection "puts"
Flow tracing
Replace proc to provide a graphical display of flow of a script.
gdb
GDBase
Offline parallel debugger; works by collecting user-specified data during the execution of a job and storing it in a database, which is available for offline inspection. Also includes dynamic breakpoint API, which allows attaching Tcl scripts to breakpoints to be executed when breakpoint is hit.
Guarded proc
RS: monitors or prevents redefining an existing proc
Tkinspect
a stand alone application that queries a running Tk application and then displays its state. This allows you to display current variable values and modify procs or variables. A Tix-enabled version of it is in TixInspect. The Tcl Dev Kit provides an enhanced version of TkInspect since release 2.5.
TkCon
[2]: by Jeff Hobbs. A great way to interact with a running Tcl/Tk application. It can be attached to any Tcl/Tk interpreter or namespace and allows any modification. This application comes bundled with ActiveTcl and therefore also with Tcl Dev Kit. Sports facilities such as idedebug and observe, which provide sophisticated breakpoint and tracing facilities, and hot errors, which displays the source of the proc in dig-down style
Tracing with enterstep
How to limit the output from tracing, plus a method for performing intelligent single-stepping without modifying the source.
INSPECT app
valgrind
Electric Fence
PED
procstep
A drop-in replacement for proc that provides a hook prior to the evaluation of command, and another hook for exceptional return codes.
RamDebugger
A graphical debugger/IDE.
Yet another Tcl debugger
Tagma Debugger
A rewrite of Yet another Tcl debugger.
TclPro
A popular open-source debugger originally sold by Scriptics. Provides not only static and dynamic debugging aids, but similar to [basekits], also a way to create a single distribution file that contain all the pieces one needs to execute a Tcl program.
Tuba
providing source code viewing as you step thru the code, breakpoints on specific lines and procs, and ability to set watchpoints on variables
TDebug
a Tk based debugger that is sourced into your script. Works conceptually like the emacs-lisp debugger. An updated version of it is in TixDebug.
The 'tracecommand' extension
based on a patch [3] [does Vince Darley have a more recent version of this?] to the Tcl core, is available from the scriptics bug database [we need a URL here]. It can be used to dump before/after command+argument+result evaluations both globally or only inside a given command or procedure. It is similar to the 'trace dump' facility available in the Tcl-scripted MacOS editor 'Alpha'.
jTcl
a Java-like object interface which provides debugging facilities. escargo 2004-02-04: dead link.
WAD
(Wrapped Application Debugger) is an embedded debugging system that is intended to simplify the task of debugging scripting language extensions. It does this by converting catastrophic errors such as segmentation faults and failed assertions into scripting language exceptions. This, in turn, allows a scripting language interpreter to generate an informative cross-language stack trace. By the author of SWIG.

Publications  edit

A Debugging Primer
an excerpt Debugging: The 9 Indispensable Rules For Finding Even the Most Elusive Software and Hardware Problems, David J. Agans
How to be a Programmer: A Short, Comprehensive, and Personal Summary, Robert L. Read, 2002
PYK 2012-12: a quick glance-through indicates that this is worth the read. Others have received it positively as well.

See Also  edit

C compiled image processing on an interactive Bwise canvas
Commonly encountered problems in Tcl
Debugging Aid For Production Code
Debugging Expect programs
debug with trace
Dynamic Debugger
A strange breed. For whatever reason, many programmers are either unfamilar or dissatisfied with most of the products in this category.
Debugging via introspection
Effective ways to request help with Tcl-related problems
Favorite debugging techniques applicable to Tcl
Help! My Tcl application just crashed!
How to debug memory faults in Tcl and extensions
Leak Hunt (C level)
List the call stack
Memory introspection
Important when trying to find bugs going into the C-level, especially hard to pin-down memory trouble.
Pstack
Displays the calling sequence for a proc.
regular expression debugging tips
Static syntax analysis
Static code checkers are tools which read your Tcl code and attempt to identify either real, or potential, problems. This is similar to the Unix lint command.
Steppin' out
uses Tcl's own command tracing
traceproc helper
specify a list of commands to monitor, and see the actual arguments passed to the commands when they are run, as well as the result.
traceback
what debugging tools are available to a Tcl programmer
Whole-Script Tracing

Components with Debugging Features  edit

Tcl itself
provides enhanced command tracing since release 8.4 (See TIP #62). Example of usage is at Steppin' out.
BLT
comes with several useful debugging commands.
TclX
comes with commands for profiling and debugging facilities, for example cmdtrace. Break down program runtime by procedure.
SNTL
includes a debugging message system.
Source Navigator
an IDE with code comprehension features. It is written in Tcl/Tk/itcl, but allows you to understand code written in a wide variety of languages.

Projects  edit

GSoC Idea: Debugging tools for NRE