Question

In Perl to perform a hash update based on arrays of keys and values I can do something like:

@hash{'key1','key2','key3'} = ('val1','val2','val3');

In Ruby I could do something similar in a more complicated way:

hash.merge!(Hash[ *[['key1','key2','key3'],['val1','val2','val3']].transpose ])

OK but I doubt the effectivity of such procedure.

Now I would like to do a more complex assignment in a single line.

Perl example:

(@hash{'key1','key2','key3'}, $key4) = &some_function();

I have no idea if such a thing is possible in some simple Ruby way. Any hints?

For the Perl impaired, @hash{'key1','key2','key3'} = ('a', 'b', 'c') is a hash slice and is a shorthand for something like this:

$hash{'key1'} = 'a';
$hash{'key2'} = 'b';
$hash{'key3'} = 'c';

Answer 1

You could redefine []= to support this:

class Hash
  def []=(*args)
    *keys, vals = args # if this doesn't work in your version of ruby, use "keys, vals = args[0...-1], args.last"
    merge! Hash[keys.zip(vals.respond_to?(:each) ? vals : [vals])]
  end
end

Now use

myhash[:key1, :key2, :key3] = :val1, :val2, :val3
# or
myhash[:key1, :key2, :key3] = some_method_returning_three_values
# or even
*myhash[:key1, :key2, :key3], local_var = some_method_returning_four_values