in reply to Accept user options with defaults and report unknowns.

I would generalize that a bit unless I only need it once. 
sub get_unknown_keys (\%;) {
    my $hash = shift;

    my %allow;
    @allow{keys %$hash} = ();
    delete @allow{@_};

    return keys %allow;
}

sub func {
    my %arg = ( foo => 1, bar => 'baz', quux => 42 );
    my @allow = keys %arg;
    %arg = (%arg, @_);

    if(my @unknown = get_unknown_keys %arg, @allow) {
        carp "Ignoring unkown parameters: @unknown";
        delete @arg{@unknown};
    }

    # do stuff.
}

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I have to say I quite like the way delete @arg{@unknown} reads.

Makeshifts last the longest.

Replies are listed 'Best First'.
Re: Re: Accept user options with defaults and report unknowns.
by BrowserUk (Patriarch) on May 30, 2003 at 03:37 UTC

    Part of me agree's, and enevitably, part doesn't.

    Three lines repeated twice becomes a sub? Use the sub in two modules, it becomes a module in its own right? Then it need pod, and a name and hell, I might as well throw in some validation of the values, so I need an api. Might as well make it OO. Oops! I re-invented Params::Validate.

    Now why did I reject Params::Validate above? Oh. because I couldn't see the point in replacing 3 lines with a module and 3 lines. 

    use My::Params::Validate;
my $validator = My::Params::Validate->new(
    Foo=>[ qw[foo|bar|qux] ],
    Bar=>[ 100 .. 1000 ],
    Qux=>[ 2e9, 3e8 ],
);

sub myfunction{
   my %opts = $validator %defs, @_;
...
}

    [download]

    Ah! But now I need some code to validate the arguements to My::Params::Validate.

    Should I subclass it? Use a virtual base class? What about exception handling?

    OMG - I just re-invented Java:)

    I do like delete @args{@unknown} (Note the S. I'll have to see if I can work that in somewhere:)

    Examine what is said, not who speaks.
    "Efficiency is intelligent laziness." -David Dunham
    "When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller


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