Trace(3pm) User Contributed Perl Documentation Trace(3pm)
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
";
print "Statement 2 at line 5
";
print "Call to sub x returns ", &x(), " at line 6.
";
exit 0;
sub x {
print "In sub x at line 12.
";
return 13;
}
Then the "Trace" output will look like this:
>> ./test:4: print "Statement 1 at line 4
";
>> ./test:5: print "Statement 2 at line 5
";
>> ./test:6: print "Call to sub x returns ", &x(), " at line 6.
";
>> ./test:12: print "In sub x at line 12.
";
>> ./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
o You should be able to send the trace output to the filehandle of your choice.
o You should be able to specify the format of the output.
o 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.
perl v5.14.2 2012-02-16 Trace(3pm)
