lib/perl5/5.6.1/assert.pl

   1 # assert.pl
   2 # tchrist@convex.com (Tom Christiansen)
   3 #
   4 # Usage:
   5 #
   6 #     &assert('@x > @y');
   7 #     &assert('$var > 10', $var, $othervar, @various_info);
   8 #
   9 # That is, if the first expression evals false, we blow up.  The
  10 # rest of the args, if any, are nice to know because they will
  11 # be printed out by &panic, which is just the stack-backtrace
  12 # routine shamelessly borrowed from the perl debugger.
  13
  14 sub assert {
  15     &panic("ASSERTION BOTCHED: $_[$[]",$@) unless eval $_[$[];
  16 }
  17
  18 sub panic {
  19     package DB;
  20
  21     select(STDERR);
  22
  23     print "\npanic: @_\n";
  24
  25     exit 1 if $] <= 4.003;  # caller broken
  26
  27     # stack traceback gratefully borrowed from perl debugger
  28
  29     local $_;
  30     my $i;
  31     my ($p,$f,$l,$s,$h,$a,@a,@frames);
  32     for ($i = 0; ($p,$f,$l,$s,$h,$w) = caller($i); $i++) {
  33         @a = @args;
  34         for (@a) {
  35             if (/^StB\000/ && length($_) == length($_main{'_main'})) {
  36                 $_ = sprintf("%s",$_);
  37             }
  38             else {
  39                 s/'/\\'/g;
  40                 s/([^\0]*)/'$1'/ unless /^-?[\d.]+$/;
  41                 s/([\200-\377])/sprintf("M-%c",ord($1)&0177)/eg;
  42                 s/([\0-\37\177])/sprintf("^%c",ord($1)^64)/eg;
  43             }
  44         }
  45         $w = $w ? '@ = ' : '$ = ';
  46         $a = $h ? '(' . join(', ', @a) . ')' : '';
  47         push(@frames, "$w&$s$a from file $f line $l\n");
  48     }
  49     for ($i=0; $i <= $#frames; $i++) {
  50         print $frames[$i];
  51     }
  52     exit 1;
  53 }
  54
  55 1;