Most concise way to assign value from hash only if it exists?

Question

I find myself often writing code like this:

if ($optionalParamsRef->{verbosity}) {
    $settingsHash{verbosity} = $optionalParamsRef->{verbosity};
}

However, it seems very verbose to repeat $optionalParamsRef->{verbosity} twice. Is there a shorter way?

Edit: Yes, I realize this is checking for true/false and not 'exists'. What I'm looking for is a concise functional equivalent to this.

Answer 1

Note you are checking $optionalParamsRef->{verbosity} for true, not exist.

Possible way to do this:

foreach my $k (qw/verbosity param1 param2 param3/) { #Enumerate keys here
     $settingsHash{$k} = $optionalParamsRef->{$k} if exists($optionalParamsRef->{$k});
}

Answer 2

As others mentioned, your code checks for false-ness. If you considered false values as non-existant, you could have used the logical or. Probably this is not what you want.

$settingsHash{verbosity} = $optionalParamsRef->{verbosity} || $default;

But maybe defined-ness is enough. It's still no check for existence, but if your hash doesn't contain undef values, this could be enough:

$settingsHash{verbosity} = $optionalParamsRef->{verbosity} // $default;

using the "new" defined-or operator // instead of the logical or ||. I know these examples are not equivalent to the code you posted because they alwas assign something, but in my experience, this is often useful, so maybe it could help.