1 | package Fatal; |
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2 | |
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3 | use 5.005_64; |
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4 | use Carp; |
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5 | use strict; |
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6 | our($AUTOLOAD, $Debug, $VERSION); |
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7 | |
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8 | $VERSION = 1.02; |
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9 | |
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10 | $Debug = 0 unless defined $Debug; |
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11 | |
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12 | sub import { |
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13 | my $self = shift(@_); |
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14 | my($sym, $pkg); |
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15 | my $void = 0; |
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16 | $pkg = (caller)[0]; |
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17 | foreach $sym (@_) { |
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18 | if ($sym eq ":void") { |
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19 | $void = 1; |
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20 | } |
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21 | else { |
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22 | &_make_fatal($sym, $pkg, $void); |
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23 | } |
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24 | } |
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25 | }; |
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26 | |
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27 | sub AUTOLOAD { |
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28 | my $cmd = $AUTOLOAD; |
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29 | $cmd =~ s/.*:://; |
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30 | &_make_fatal($cmd, (caller)[0]); |
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31 | goto &$AUTOLOAD; |
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32 | } |
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33 | |
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34 | sub fill_protos { |
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35 | my $proto = shift; |
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36 | my ($n, $isref, @out, @out1, $seen_semi) = -1; |
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37 | while ($proto =~ /\S/) { |
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38 | $n++; |
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39 | push(@out1,[$n,@out]) if $seen_semi; |
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40 | push(@out, $1 . "{\$_[$n]}"), next if $proto =~ s/^\s*\\([\@%\$\&])//; |
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41 | push(@out, "\$_[$n]"), next if $proto =~ s/^\s*([*\$&])//; |
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42 | push(@out, "\@_[$n..\$#_]"), last if $proto =~ s/^\s*(;\s*)?\@//; |
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43 | $seen_semi = 1, $n--, next if $proto =~ s/^\s*;//; # XXXX ???? |
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44 | die "Unknown prototype letters: \"$proto\""; |
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45 | } |
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46 | push(@out1,[$n+1,@out]); |
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47 | @out1; |
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48 | } |
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49 | |
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50 | sub write_invocation { |
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51 | my ($core, $call, $name, $void, @argvs) = @_; |
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52 | if (@argvs == 1) { # No optional arguments |
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53 | my @argv = @{$argvs[0]}; |
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54 | shift @argv; |
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55 | return "\t" . one_invocation($core, $call, $name, $void, @argv) . ";\n"; |
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56 | } else { |
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57 | my $else = "\t"; |
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58 | my (@out, @argv, $n); |
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59 | while (@argvs) { |
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60 | @argv = @{shift @argvs}; |
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61 | $n = shift @argv; |
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62 | push @out, "$ {else}if (\@_ == $n) {\n"; |
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63 | $else = "\t} els"; |
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64 | push @out, |
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65 | "\t\treturn " . one_invocation($core, $call, $name, $void, @argv) . ";\n"; |
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66 | } |
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67 | push @out, <<EOC; |
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68 | } |
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69 | die "$name(\@_): Do not expect to get ", scalar \@_, " arguments"; |
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70 | EOC |
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71 | return join '', @out; |
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72 | } |
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73 | } |
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74 | |
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75 | sub one_invocation { |
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76 | my ($core, $call, $name, $void, @argv) = @_; |
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77 | local $" = ', '; |
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78 | if ($void) { |
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79 | return qq/(defined wantarray)?$call(@argv): |
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80 | $call(@argv) || croak "Can't $name(\@_)/ . |
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81 | ($core ? ': $!' : ', \$! is \"$!\"') . '"' |
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82 | } else { |
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83 | return qq{$call(@argv) || croak "Can't $name(\@_)} . |
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84 | ($core ? ': $!' : ', \$! is \"$!\"') . '"'; |
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85 | } |
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86 | } |
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87 | |
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88 | sub _make_fatal { |
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89 | my($sub, $pkg, $void) = @_; |
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90 | my($name, $code, $sref, $real_proto, $proto, $core, $call); |
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91 | my $ini = $sub; |
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92 | |
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93 | $sub = "${pkg}::$sub" unless $sub =~ /::/; |
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94 | $name = $sub; |
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95 | $name =~ s/.*::// or $name =~ s/^&//; |
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96 | print "# _make_fatal: sub=$sub pkg=$pkg name=$name void=$void\n" if $Debug; |
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97 | croak "Bad subroutine name for Fatal: $name" unless $name =~ /^\w+$/; |
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98 | if (defined(&$sub)) { # user subroutine |
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99 | $sref = \&$sub; |
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100 | $proto = prototype $sref; |
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101 | $call = '&$sref'; |
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102 | } elsif ($sub eq $ini) { # Stray user subroutine |
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103 | die "$sub is not a Perl subroutine" |
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104 | } else { # CORE subroutine |
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105 | $proto = eval { prototype "CORE::$name" }; |
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106 | die "$name is neither a builtin, nor a Perl subroutine" |
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107 | if $@; |
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108 | die "Cannot make a non-overridable builtin fatal" |
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109 | if not defined $proto; |
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110 | $core = 1; |
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111 | $call = "CORE::$name"; |
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112 | } |
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113 | if (defined $proto) { |
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114 | $real_proto = " ($proto)"; |
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115 | } else { |
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116 | $real_proto = ''; |
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117 | $proto = '@'; |
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118 | } |
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119 | $code = <<EOS; |
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120 | sub$real_proto { |
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121 | local(\$", \$!) = (', ', 0); |
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122 | EOS |
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123 | my @protos = fill_protos($proto); |
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124 | $code .= write_invocation($core, $call, $name, $void, @protos); |
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125 | $code .= "}\n"; |
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126 | print $code if $Debug; |
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127 | { |
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128 | no strict 'refs'; # to avoid: Can't use string (...) as a symbol ref ... |
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129 | $code = eval("package $pkg; use Carp; $code"); |
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130 | die if $@; |
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131 | no warnings; # to avoid: Subroutine foo redefined ... |
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132 | *{$sub} = $code; |
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133 | } |
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134 | } |
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135 | |
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136 | 1; |
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137 | |
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138 | __END__ |
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139 | |
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140 | =head1 NAME |
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141 | |
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142 | Fatal - replace functions with equivalents which succeed or die |
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143 | |
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144 | =head1 SYNOPSIS |
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145 | |
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146 | use Fatal qw(open close); |
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147 | |
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148 | sub juggle { . . . } |
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149 | import Fatal 'juggle'; |
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150 | |
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151 | =head1 DESCRIPTION |
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152 | |
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153 | C<Fatal> provides a way to conveniently replace functions which normally |
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154 | return a false value when they fail with equivalents which raise exceptions |
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155 | if they are not successful. This lets you use these functions without |
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156 | having to test their return values explicitly on each call. Exceptions |
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157 | can be caught using C<eval{}>. See L<perlfunc> and L<perlvar> for details. |
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158 | |
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159 | The do-or-die equivalents are set up simply by calling Fatal's |
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160 | C<import> routine, passing it the names of the functions to be |
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161 | replaced. You may wrap both user-defined functions and overridable |
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162 | CORE operators (except C<exec>, C<system> which cannot be expressed |
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163 | via prototypes) in this way. |
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164 | |
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165 | If the symbol C<:void> appears in the import list, then functions |
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166 | named later in that import list raise an exception only when |
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167 | these are called in void context--that is, when their return |
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168 | values are ignored. For example |
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169 | |
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170 | use Fatal qw/:void open close/; |
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171 | |
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172 | # properly checked, so no exception raised on error |
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173 | if(open(FH, "< /bogotic") { |
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174 | warn "bogo file, dude: $!"; |
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175 | } |
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176 | |
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177 | # not checked, so error raises an exception |
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178 | close FH; |
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179 | |
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180 | =head1 AUTHOR |
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181 | |
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182 | Lionel.Cons@cern.ch |
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183 | |
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184 | prototype updates by Ilya Zakharevich ilya@math.ohio-state.edu |
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185 | |
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186 | =cut |
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