Devel::ptkdb3pm

File Menu

About...

Presents a dialog box telling you about the version of ptkdb. It recovers your OS name, version of perl, version of Tk, and some other information

Open

Presents a list of files that are part of the invoked perl script. Selecting a file from this list will present this file in the text window.

Save Config...

Requires Data::Dumper. Prompts for a filename to save the configuration to. Saves the breakpoints, expressions, eval text and window geometry. If the name given as the default is used and the script is reinvoked, this configuration will be reloaded automatically.

    B<NOTE:>  You may find this preferable to using

Restore Config...

Requires Data::Dumper. Prompts for a filename to restore a configuration saved with the "Save Config..." menu item.

Goto Line...

Prompts for a line number. Pressing the "Okay" button sends the window to the line number entered. item Find Text...

Prompts for text to search for. Options include forward search, backwards search, and regular expression searching.

Quit

 Causes the debugger and the target script to exit.

Control Menu

Run

The debugger allows the script to run to the next breakpoint or until the script exits. item Run To Here

Runs the debugger until it comes to wherever the insertion cursor in text window is placed.

Set Breakpoint

Sets a breakpoint on the line at the insertion cursor. item Clear Breakpoint

Remove a breakpoint on the at the insertion cursor.

Clear All Breakpoints

Removes all current breakpoints

Step Over

Causes the debugger to step over the next line. If the line is a subroutine call it steps over the call, stopping when the subroutine returns.

Step In

Causes the debugger to step into the next line. If the line is a subroutine call it steps into the subroutine, stopping at the first executable line within the subroutine.

Return

Runs the script until it returns from the currently executing subroutine.

Restart

Saves the breakpoints and expressions in a temporary file and restarts the script from the beginning. CAUTION: This feature will not work properly with debugging of CGI Scripts.

Stop On Warning

When "-w" is enabled the debugger will stop when warnings such as, "Use of uninitialized value at undef_warn.pl line N" are encountered. The debugger will stop on the NEXT line of execution since the error can't be detected until the current line has executed.

This feature can be turned on at startup by adding:

$DB::ptkdb::stop_on_warning = 1 ;

to a .ptkdbrc file

Data Menu

Enter Expression

When an expression is entered in the "Enter Expression:" text box, selecting this item will enter the expression into the expression list. Each time the debugger stops this expression will be evaluated and its result updated in the list window.

Delete Expression

 Deletes the highlighted expression in the expression window.

Delete All Expressions

 Delete all expressions in the expression window.

Expression Eval Window

Pops up a two pane window. Expressions of virtually unlimitted length can be entered in the top pane. Pressing the 'Eval' button will cause the expression to be evaluated and its placed in the lower pane. If Data::Dumper is available it will be used to format the resulting text. Undo is enabled for the text in the upper pane.

HINT: You can enter multiple expressions by separating them with commas.

Use Data::Dumper for Eval Window

Enables or disables the use of Data::Dumper for formatting the results of expressions in the Eval window.

Stack Menu

Maintains a list of the current subroutine stack each time the debugger stops. Selecting an item from this menu will set the text in the code window to that particular subourtine entry point.

Bookmarks Menu

Maintains a list of bookmarks. The booksmarks are saved in ~/.ptkdb_bookmarks

Add Bookmark

Adds a bookmark to the bookmark list.

.ptkdbrc

If this file is present in ~/ or in the directory where perl is invoked the file will be read and executed as a perl script before the debugger makes its initial stop at startup. There are several 'api' calls that can be used with such scripts. There is an internal variable $DB::no_stop_at_start that may be set to non-zero to prevent the debugger from stopping at the first line of the script. This is useful for debugging CGI scripts.

There is a system ptkdbrc file in $PREFIX/lib/perl5/$VERS/Devel/ptkdbrc

brkpt($fname, @lines)

Sets breakspoints on the list of lines in $fname. A warning message is generated if a line is not breakable.

condbrkpt($fname, @($line, $expr) )

Sets conditional breakpoints in $fname on pairs of $line and $expr. A warning message is generated if a line is not breakable. NOTE: the validity of the expression will not be determined until execution of that particular line.

brkonsub(@names)

Sets a breakpoint on each subroutine name listed. A warning message is generated if a subroutine does not exist. NOTE: for a script with no other packages the default package is "main::" and the subroutines would be "main::mySubs".

brkonsub_regex(@regExprs)

Uses the list of @regExprs as a list of regular expressions to set breakpoints. Sets breakpoints on every subroutine that matches any of the listed regular expressions.

textTagConfigure(tag, ?option?, ?value?)

Allows the user to format the text in the code window. The option value pairs are the same values as the option for the tagConfigure method documented in Tk::Text. Currently the following tags are in effect:

    'code'               Format for code in the text pane
    'stoppt'             Format applied to the line where the debugger is currently stopped
    'breakableLine'      Format applied to line numbers where the code is 'breakable'
    'nonbreakableLine'   Format applied to line numbers where the code is no breakable
    'breaksetLine'       Format applied to line numbers were a breakpoint is set
    'breakdisabledLine'  Format applied to line numbers were a disabled breakpoint is set
    'search_tag'         Format applied to text when located by a search.  
 Example:
 #
 # Turns off the overstrike on lines that you can't set a breakpoint on
 # and makes the text color yellow. 
 #
    textTagConfigure('nonbreakableLine', -overstrike => 0, -foreground => "yellow") ;

add_exprs(@exprList)

Add a list of expressions to the 'Exprs' window. NOTE: use the single quote character \' to prevent the expression from being "evaluated" in the string context.

  Example:
    #
    # Adds the $_ and @_ expressions to the active list
    #
    add_exprs('$_', '@_') ;

Debugging Other perlTk Applications

ptkdb can be used to debug other perlTk applications if some cautions are observed. Basically, do not click the mouse in the application's window(s) when you've entered the debugger and do not click in the debugger's window(s) while the application is running. Doing either one is not necessarily fatal, but it can confuse things that are going on and produce unexpected results.

Be aware that most perlTk applications have a central event loop. User actions, such as mouse clicks, key presses, window exposures, etc will generate 'events' that the script will process. When a perlTk application is running, its 'MainLoop' call will accept these events and then dispatch them to appropriate callbacks associated with the appropriate widgets.

Ptkdb has its own event loop that runs whenever you've stopped at a breakpoint and entered the debugger. However, it can accept events that are generated by other perlTk windows and dispatch their callbacks. The problem here is that the application is supposed to be 'stopped', and logically the application should not be able to process events.

A future version of ptkdb will have an extension that will 'filter' events so that application events are not processed while the debugger is active, and debugger events will not be processed while the target script is active.

Debugging CGI Scripts

One advantage of ptkdb over the builtin debugger(-d) is that it can be used to debug CGI perl scripts as they run on a web server. Be sure that that your web server's perl instalation includes Tk.

Change your

  #! /usr/local/bin/perl

to

  #! /usr/local/bin/perl -d:ptkdb

TIP: You can debug scripts remotely if you're using a unix based Xserver and where you are authoring the script has an Xserver. The Xserver can be another unix workstation, a Macintosh or Win32 platform with an appropriate X package. In your script insert the following BEGIN subroutine:

    sub BEGIN {
      $ENV{'DISPLAY'} = "myHostname:0.0" ;
    }

Be sure that your web server has permission to open windows on your Xserver (see the xhost manpage).

Access your web page with your browswer and 'submit' the script as normal. The ptkdb window should appear on myHostname's monitor. At this point you can start debugging your script. Be aware that your browser may timeout waiting for the script to run.

To expedite debugging you may want to setup your breakpoints in advance with a .ptkdbrc file and use the $DB::no_stop_at_start variable. NOTE: for debugging web scripts you may have to have the .ptkdbrc file installed in the server account's home directory (~www) or whatever username your webserver is running under. Also try installing a .ptkdbrc file in the same directory as the target script.