package yDebug;

our $tracefile;

$|=1; # or not. You'll need that for piping uncluttered STDOUT and STDERR into a pager.

sub import {
    shift;
    if (@_) {
        $tracefile = shift;
        warn __PACKAGE__.": tracing to '$tracefile'\n";
        open my $fh, '>', $tracefile or die "open '$tracefile': $!";
        $Devel::Trace::FH = $fh;
        my $oldfh = select $fh; $| = 1; select $oldfh; 
    }
}

$Devel::Trace::FORMAT = \&format;
@Devel::Trace::ORDER  = (0..10,-3,-2,-1);

my ($file,$pkg,$sub);
sub format {
    my ($package, $filename, $line, $subroutine, $hasargs,
        $wantarray, $evaltext, $is_require, $hints, $bitmask,
        $hinthash) = @_;
    ($from, $db_args, $codeline) = @_[-3..-1];
    my $ret;
    if ($filename ne $file) {
        $ret = "# file $filename\n";
        $file = $filename;
    }
    if ($package and $package ne $pkg) {
        $ret .= "# package $package\n";
        $pkg = $package;
    }
    if ($subroutine) {
        if($sub ne $subroutine) {
            $ret .= "# -> $subroutine (". join(', ',@$db_args).")";
            $ret .= ' called in '.
                    ($wantarray ? 'LIST' :
                        defined $wantarray ? 'SCALAR' : 'VOID'
                    ) . " context\n";
            $sub = $subroutine;
        }
    } else {
        $sub = '';
    }
    $ret .= sprintf "%6s", $line;
    if ($from) {
        chomp $codeline;
        $ret .= " >> $codeline # (@$from[0..2])\n";
    } else {
        $ret .= " >> $codeline";
    }
    $ret .= "-" x 78 . "\n";
    $ret;
}
1;