new

/*
 *  call-seq:
 *     Hash.new                          => hash
 *     Hash.new(obj)                     => aHash
 *     Hash.new {|hash, key| block }     => aHash
 *
 *  Returns a new, empty hash. If this hash is subsequently accessed by
 *  a key that doesn't correspond to a hash entry, the value returned
 *  depends on the style of <code>new</code> used to create the hash. In
 *  the first form, the access returns <code>nil</code>. If
 *  <i>obj</i> is specified, this single object will be used for
 *  all <em>default values</em>. If a block is specified, it will be
 *  called with the hash object and the key, and should return the
 *  default value. It is the block's responsibility to store the value
 *  in the hash if required.
 *
 *     h = Hash.new("Go Fish")
 *     h["a"] = 100
 *     h["b"] = 200
 *     h["a"]           #=> 100
 *     h["c"]           #=> "Go Fish"
 *     # The following alters the single default object
 *     h["c"].upcase!   #=> "GO FISH"
 *     h["d"]           #=> "GO FISH"
 *     h.keys           #=> ["a", "b"]
 *
 *     # While this creates a new default object each time
 *     h = Hash.new { |hash, key| hash[key] = "Go Fish: #{key}" }
 *     h["c"]           #=> "Go Fish: c"
 *     h["c"].upcase!   #=> "GO FISH: C"
 *     h["d"]           #=> "Go Fish: d"
 *     h.keys           #=> ["c", "d"]
 *
 */

static VALUE
rb_hash_initialize(argc, argv, hash)
    int argc;
    VALUE *argv;
    VALUE hash;
{
    VALUE ifnone;

    rb_hash_modify(hash);
    if (rb_block_given_p()) {
        if (argc > 0) {
            rb_raise(rb_eArgError, "wrong number of arguments");
        }
        RHASH(hash)->ifnone = rb_block_proc();
        FL_SET(hash, HASH_PROC_DEFAULT);
    }
    else {
        rb_scan_args(argc, argv, "01", &ifnone);
        RHASH(hash)->ifnone = ifnone;
    }

    return hash;
}