NAME

App::Framework::Debugging - Debugging tools/methods

DESCRIPTION

There are some mechanisms built into the application framework that provide methods of getting extra script debugging information. I have also described below some of the external tools I've found useful when debugging my scripts.

Printing

The application framework object (referred to as $app here) has a prt_data method that provides a hierarchical printout of HASHes, ARRAYs, and scalars. This method always outputs.

An alternative is to use the debug_prt method. This prints out information, but only if the debug command line option has been set. You may also specify the debug level above which the debug option has to be set before any output appears. Some examples are:

    sub app
    {
        my ($app, $opts_href, $args_href) = @_ ;
        
        my %a_hash ;
        
        # always print out a string followed by the options HASH
        $app->prt_data("Options=", $opts_href) ;
    
        # always print out a string followed by the local HASH
        $app->prt_data("Options=", \%a_hash) ;
    
    
        ## do the same but only when the script is called with '-debug 1'
        $app->debug_prt( ["Options=", $opts_href] ) ;
        
        ## this only shows when the script is called with '-debug 2' or above
        $app->debug_prt( ["Options=", $opts_href], 2 ) ;
    
    }    
    

Debugger

In certain circumstances, I've had to resort to a GUI debugger. The one I use is Devel::ptkdb at http://search.cpan.org/~aepage/Devel-ptkdb/ and you run your script as:

    perl -d:ptkdb your_script.pl

Note that on startup you won't see the various Feature modules loaded up in the 'open file' menu. This is because the framework dynamically loads them. If you set a breakpoint in your app() subroutine, then they are all loaded by then.

Profiler

I have also found it useful to profile scripts to find whatever is slowing the script down. I've found that the default Perl profiler (Devel::prof) doesn't like my framework! The alternative I use is Devel::FastProf at http://search.cpan.org/~salva/Devel-FastProf/ which produces counts per module line. You gather the data as:

    perl -d:FastProf your_script.pl

to produce a binary file fastprof.out which you convert into text using fprofpp:

    fprofpp > your_script.txt

As I also prefer to see which function the line number is refering to, I use my script (using the App::Framework Filter extension!) to post-process the data. My script is available from ftp://www.cpan.org/authors/id/S/SD/SDPRICE/Examples/App-Framework/Filter/ and is run as:

    fprofpp-filter your_script.txt