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| 1 | +#!/uns/bin/perl |
| 2 | + |
| 3 | +package checkargs; |
| 4 | +require 5.004; # uses "for my $var" |
| 5 | +require Exporter; |
| 6 | +@ISA = qw(Exporter); |
| 7 | +@EXPORT = qw(check_args check_args_range check_args_at_least); |
| 8 | +use strict; |
| 9 | +use Carp; |
| 10 | + |
| 11 | +=head1 NAME |
| 12 | +
|
| 13 | +checkargs -- Provide rudimentary argument checking for perl5 functions |
| 14 | +
|
| 15 | +=head1 SYNOPSIS |
| 16 | +
|
| 17 | + check_args(cArgsExpected, @_) |
| 18 | + check_args_range(cArgsMin, cArgsMax, @_) |
| 19 | + check_args_at_least(cArgsMin, @_) |
| 20 | +where "@_" should be supplied literally. |
| 21 | +
|
| 22 | +=head1 DESCRIPTION |
| 23 | +
|
| 24 | +As the first line of user-written subroutine foo, do one of the following: |
| 25 | +
|
| 26 | + my ($arg1, $arg2) = check_args(2, @_); |
| 27 | + my ($arg1, @rest) = check_args_range(1, 4, @_); |
| 28 | + my ($arg1, @rest) = check_args_at_least(1, @_); |
| 29 | + my @args = check_args_at_least(0, @_); |
| 30 | +
|
| 31 | +These functions may also be called for side effect (put a call to one |
| 32 | +of the functions near the beginning of the subroutine), but using the |
| 33 | +argument checkers to set the argument list is the recommended usage. |
| 34 | +
|
| 35 | +The number of arguments and their definedness are checked; if the wrong |
| 36 | +number are received, the program exits with an error message. |
| 37 | +
|
| 38 | +=head1 AUTHOR |
| 39 | +
|
| 40 | +Michael D. Ernst <F<[email protected]>> |
| 41 | +
|
| 42 | +=cut |
| 43 | + |
| 44 | +## Need to check that use of caller(1) really gives desired results. |
| 45 | +## Need to give input chunk information. |
| 46 | +## Is this obviated by Perl 5.003's declarations? Not entirely, I think. |
| 47 | + |
| 48 | +sub check_args ( $@ ) |
| 49 | +{ |
| 50 | + my ($num_formals, @args) = @_; |
| 51 | + my ($pack, $file_arg, $line_arg, $subname, $hasargs, $wantarr) = caller(1); |
| 52 | + if (@_ < 1) { croak "check_args needs at least 7 args, got ", scalar(@_), ": @_\n "; } |
| 53 | + if ((!wantarray) && ($num_formals != 0)) |
| 54 | + { croak "check_args called in scalar context"; } |
| 55 | + # Can't use croak below here: it would only go out to caller, not its caller |
| 56 | + my $num_actuals = @args; |
| 57 | + if ($num_actuals != $num_formals) |
| 58 | + { die "$file_arg:$line_arg: function $subname expected $num_formals argument", |
| 59 | + (($num_formals == 1) ? "" : "s"), |
| 60 | + ", got $num_actuals", |
| 61 | + (($num_actuals == 0) ? "" : ": @args"), |
| 62 | + "\n"; } |
| 63 | + for my $index (0..$#args) |
| 64 | + { if (!defined($args[$index])) |
| 65 | + { die "$file_arg:$line_arg: function $subname undefined argument ", $index+1, ": @args[0..$index-1]\n"; } } |
| 66 | + return @args; |
| 67 | +} |
| 68 | + |
| 69 | +sub check_args_range ( $$@ ) |
| 70 | +{ |
| 71 | + my ($min_formals, $max_formals, @args) = @_; |
| 72 | + my ($pack, $file_arg, $line_arg, $subname, $hasargs, $wantarr) = caller(1); |
| 73 | + if (@_ < 2) { croak "check_args_range needs at least 8 args, got ", scalar(@_), ": @_"; } |
| 74 | + if ((!wantarray) && ($max_formals != 0) && ($min_formals !=0) ) |
| 75 | + { croak "check_args_range called in scalar context"; } |
| 76 | + # Can't use croak below here: it would only go out to caller, not its caller |
| 77 | + my $num_actuals = @args; |
| 78 | + if (($num_actuals < $min_formals) || ($num_actuals > $max_formals)) |
| 79 | + { die "$file_arg:$line_arg: function $subname expected $min_formals-$max_formals arguments, got $num_actuals", |
| 80 | + ($num_actuals == 0) ? "" : ": @args", "\n"; } |
| 81 | + for my $index (0..$#args) |
| 82 | + { if (!defined($args[$index])) |
| 83 | + { die "$file_arg:$line_arg: function $subname undefined argument ", $index+1, ": @args[0..$index-1]\n"; } } |
| 84 | + return @args; |
| 85 | +} |
| 86 | + |
| 87 | +sub check_args_at_least ( $@ ) |
| 88 | +{ |
| 89 | + my ($min_formals, @args) = @_; |
| 90 | + my ($pack, $file_arg, $line_arg, $subname, $hasargs, $wantarr) = caller(1); |
| 91 | + # Don't do this, because we want every sub to start with a call to check_args* |
| 92 | + # if ($min_formals == 0) |
| 93 | + # { die "Isn't it pointless to check for at least zero args to $subname?\n"; } |
| 94 | + if (scalar(@_) < 1) |
| 95 | + { croak "check_args_at_least needs at least 1 arg, got ", scalar(@_), ": @_"; } |
| 96 | + if ((!wantarray) && ($min_formals != 0)) |
| 97 | + { croak "check_args_at_least called in scalar context"; } |
| 98 | + # Can't use croak below here: it would only go out to caller, not its caller |
| 99 | + my $num_actuals = @args; |
| 100 | + if ($num_actuals < $min_formals) |
| 101 | + { die "$file_arg:$line_arg: function $subname expected at least $min_formals argument", |
| 102 | + ($min_formals == 1) ? "" : "s", |
| 103 | + ", got $num_actuals", |
| 104 | + ($num_actuals == 0) ? "" : ": @args", "\n"; } |
| 105 | + for my $index (0..$#args) |
| 106 | + { if (!defined($args[$index])) |
| 107 | + { warn "$file_arg:$line_arg: function $subname undefined argument ", $index+1, ": @args[0..$index-1]\n"; last; } } |
| 108 | + return @args; |
| 109 | +} |
| 110 | + |
| 111 | +1; # successful import |
| 112 | +__END__ |
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