#!/uns/bin/perl -w
package util_mde;
require 5.003;			# uses prototypes
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw( hash_value_replace
	     mail_file mail system_or_die );

use checkargs;

use strict;
use Carp;
use English;


###########################################################################
### Hashes
###

sub hash_value_replace ( $$% )
{ my ($old_val, $new_val, %hash) = check_args_at_least(2, @_);
  for my $key (keys %hash)	# precompute, so side effects don't affect
    { if ($hash{$key} eq $old_val)
	{ $hash{$key} = $new_val; } }
  return %hash;
}



###########################################################################
### External processes
###

sub mail_file ( $$$ )
{ my ($address, $subject, $filename) = check_args(3, @_);
  return system_or_die("/bin/mail -s '$subject' $address < $filename");
}

sub mail ( $$$ )
{ my ($address, $subject, $body) = check_args(3, @_);
  return system_or_die("echo '$body' | /bin/mail -s '$subject' $address");
}

# Execute the command; die if its execution is erroneous.
sub system_or_die ( $ )
{ my ($cmd) = check_args(1, @_);
  my $result = system($cmd);
  if ($result != 0)
    { croak "Failed executing $cmd"; }
  return $result;
}

## I'm not convinced this versin is performing correctly.

# my $sod_count = 0;
# 
# # Execute the command; die if its execution is erroneous.
# sub system_or_die ( $ )
# { my ($cmd) = check_args(1, @_);
#   my $errfile = "/tmp/sod$$.$sod_count";
#   $sod_count++;
#   my $result = system("$cmd >& $errfile");
#   if ($result != 0)
#     { # It doesn't help to print $! here.
#       if ((-f $errfile) && !(-z $errfile))
# 	{ open(ERRS, "<$errfile");
# 	  my @err_output = <ERRS>;
# 	  close(ERRS);
# 	  unlink $errfile;
# 	  croak "Failed executing $cmd:\n@err_output"; }
#       unlink $errfile;
#       croak "Failed executing $cmd"; }
#   unlink $errfile;
#   return $result;
# }


###########################################################################
### End of file
###

# Return true to indicate success loading this package.
1;