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112 lines
4.1 KiB
Perl
112 lines
4.1 KiB
Perl
#! /usr/bin/perl
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package checkargs;
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require 5.004; # uses "for my $var"
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require Exporter;
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@ISA = qw(Exporter);
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@EXPORT = qw(check_args check_args_range check_args_at_least);
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use strict;
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use Carp;
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=head1 NAME
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checkargs -- Provide rudimentary argument checking for perl5 functions
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=head1 SYNOPSIS
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check_args(cArgsExpected, @_)
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check_args_range(cArgsMin, cArgsMax, @_)
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check_args_at_least(cArgsMin, @_)
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where "@_" should be supplied literally.
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=head1 DESCRIPTION
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As the first line of user-written subroutine foo, do one of the following:
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my ($arg1, $arg2) = check_args(2, @_);
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my ($arg1, @rest) = check_args_range(1, 4, @_);
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my ($arg1, @rest) = check_args_at_least(1, @_);
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my @args = check_args_at_least(0, @_);
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These functions may also be called for side effect (put a call to one
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of the functions near the beginning of the subroutine), but using the
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argument checkers to set the argument list is the recommended usage.
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The number of arguments and their definedness are checked; if the wrong
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number are received, the program exits with an error message.
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=head1 AUTHOR
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Michael D. Ernst <F<mernst@cs.washington.edu>>
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=cut
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## Need to check that use of caller(1) really gives desired results.
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## Need to give input chunk information.
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## Is this obviated by Perl 5.003's declarations? Not entirely, I think.
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sub check_args ( $@ )
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{
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my ($num_formals, @args) = @_;
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my ($pack, $file_arg, $line_arg, $subname, $hasargs, $wantarr) = caller(1);
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if (@_ < 1) { croak "check_args needs at least 7 args, got ", scalar(@_), ": @_\n "; }
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if ((!wantarray) && ($num_formals != 0))
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{ croak "check_args called in scalar context"; }
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# Can't use croak below here: it would only go out to caller, not its caller
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my $num_actuals = @args;
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if ($num_actuals != $num_formals)
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{ die "$file_arg:$line_arg: function $subname expected $num_formals argument",
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(($num_formals == 1) ? "" : "s"),
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", got $num_actuals",
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(($num_actuals == 0) ? "" : ": @args"),
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"\n"; }
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for my $index (0..$#args)
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{ if (!defined($args[$index]))
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{ die "$file_arg:$line_arg: function $subname undefined argument ", $index+1, ": @args[0..$index-1]\n"; } }
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return @args;
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}
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sub check_args_range ( $$@ )
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{
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my ($min_formals, $max_formals, @args) = @_;
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my ($pack, $file_arg, $line_arg, $subname, $hasargs, $wantarr) = caller(1);
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if (@_ < 2) { croak "check_args_range needs at least 8 args, got ", scalar(@_), ": @_"; }
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if ((!wantarray) && ($max_formals != 0) && ($min_formals !=0) )
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{ croak "check_args_range called in scalar context"; }
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# Can't use croak below here: it would only go out to caller, not its caller
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my $num_actuals = @args;
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if (($num_actuals < $min_formals) || ($num_actuals > $max_formals))
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{ die "$file_arg:$line_arg: function $subname expected $min_formals-$max_formals arguments, got $num_actuals",
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($num_actuals == 0) ? "" : ": @args", "\n"; }
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for my $index (0..$#args)
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{ if (!defined($args[$index]))
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{ die "$file_arg:$line_arg: function $subname undefined argument ", $index+1, ": @args[0..$index-1]\n"; } }
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return @args;
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}
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sub check_args_at_least ( $@ )
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{
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my ($min_formals, @args) = @_;
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my ($pack, $file_arg, $line_arg, $subname, $hasargs, $wantarr) = caller(1);
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# Don't do this, because we want every sub to start with a call to check_args*
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# if ($min_formals == 0)
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# { die "Isn't it pointless to check for at least zero args to $subname?\n"; }
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if (scalar(@_) < 1)
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{ croak "check_args_at_least needs at least 1 arg, got ", scalar(@_), ": @_"; }
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if ((!wantarray) && ($min_formals != 0))
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{ croak "check_args_at_least called in scalar context"; }
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# Can't use croak below here: it would only go out to caller, not its caller
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my $num_actuals = @args;
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if ($num_actuals < $min_formals)
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{ die "$file_arg:$line_arg: function $subname expected at least $min_formals argument",
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($min_formals == 1) ? "" : "s",
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", got $num_actuals",
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($num_actuals == 0) ? "" : ": @args", "\n"; }
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for my $index (0..$#args)
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{ if (!defined($args[$index]))
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{ warn "$file_arg:$line_arg: function $subname undefined argument ", $index+1, ": @args[0..$index-1]\n"; last; } }
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return @args;
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}
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1; # successful import
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__END__
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