note
duelafn
<p>It will work fine for sub parameters. You can provide a list of keys as a second parameter to lock_keys:</p>
<code>
sub whatever {
my %params = @_;
lock_keys %params, qw/ key1 key2 key3 /;
say "Got key1" if $params{key1}; # ok
say "Got key2" if $params{key2}; # ok
say "Got key3" if $params{keye}; # Oops - BOOM!
}
whatever key2 => $value2;
whatever keyq => $value1; # Hash has key 'keyq' which is not in the new key set
</code>
<p>For example, I use the following for parsing command-line options in my scripts:</p>
<code>
use Getopt::Long qw/:config bundling/;
use Hash::Util qw/ lock_keys /;
our %OPT;
my @OPT_SPEC = qw/ help|h version noact|no-act|dry-run DEBUG output|o=s /;
GetOptions \%OPT, @OPT_SPEC or ($OPT{help} = 1);
lock_keys(%OPT, map /^(\w+)/, @OPT_SPEC);
</code>
<p><b>Update 2:</b> A diligent Anonymous monk actually tested this code (actually executing proposed code - what a concept) and pointed out that the initial lock_keys suggestion is sufficient. Updated the comments in the code above to reflect this.</p>
<p><b>Update:</b> <strike>Add example where lock_keys is not quite sufficient... One could solve this in a couple ways without changing how <code>whatever</code> is called:</strike> Anonymous monk make all this unnecessary</p>
<code>
# Option 1: use Params::Validate
# Option 2:
sub whatever {
my @param_keys = qw/ key1 key2 key3 /;
my %params = @_;
$params{$_} //= undef for @param_keys;
die "Invalid usage" if @param_keys != (keys %params);
lock_keys %params;
# ...
}
# Option 3:
sub whatever {
my %expected_params = map +($_,1), qw/ key1 key2 key3 /;
my %params = @_;
for (keys %params) {
die "whatever: Unexpected named parameter $_" unless exists $expected_params{$_};
}
lock_keys %params, keys %expected_params;
# ...
}
</code>
<div class="pmsig"><div class="pmsig-53268">
<p>Good Day,<br> Dean</p>
</div></div>
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