NAME¶

Devel::Trace - Print out each line before it is executed (like "sh -x")

SYNOPSIS¶

  perl -d:Trace program

DESCRIPTION¶

If you run your program with "perl -d:Trace program", this module will print a message to standard error just before each line is executed. For example, if your program looks like this:

        #!/usr/bin/perl
        
        
        print "Statement 1 at line 4\n";
        print "Statement 2 at line 5\n";
        print "Call to sub x returns ", &x(), " at line 6.\n";
        
        exit 0;
        
        
        sub x {
          print "In sub x at line 12.\n";
          return 13;
        }

Then the "Trace" output will look like this:

        >> ./test:4: print "Statement 1 at line 4\n";
        >> ./test:5: print "Statement 2 at line 5\n";
        >> ./test:6: print "Call to sub x returns ", &x(), " at line 6.\n";
        >> ./test:12:   print "In sub x at line 12.\n";
        >> ./test:13:   return 13;
        >> ./test:8: exit 0;

This is something like the shell's "-x" option.

DETAILS¶

Inside your program, you can enable and disable tracing by doing

    $Devel::Trace::TRACE = 1;   # Enable
    $Devel::Trace::TRACE = 0;   # Disable

or

    Devel::Trace::trace('on');  # Enable
    Devel::Trace::trace('off'); # Disable

"Devel::Trace" exports the "trace" function if you ask it to:

    import Devel::Trace 'trace';

Then if you want you just say

    trace 'on';                 # Enable
    trace 'off';                # Disable

TODO¶

• You should be able to send the trace output to the filehandle of your choice.
• You should be able to specify the format of the output.
• You should be able to get the output into a string.

We'll see.

LICENSE¶

Devel::Trace 0.11 and its source code are hereby placed in the public domain.

Author¶

Mark-Jason Dominus (C<mjd-perl-trace@plover.com>), Plover Systems co. See the C<Devel::Trace.pm> Page at http://www.plover.com/~mjd/perl/Trace for news and upgrades.