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instance method

Set#<=>

(untyped other) -> 0?

self <=> object → -1, 0, 1, or nil

static VALUE
set_i_compare(VALUE set, VALUE other)
{
    if (rb_obj_is_kind_of(other, rb_cSet)) {
        size_t set_size = RSET_SIZE(set);
        size_t other_size = RSET_SIZE(other);

        if (set_size < other_size) {
            if (set_le(set, other) == Qtrue) {
                return INT2NUM(-1);
            }
        }
        else if (set_size > other_size) {
            if (set_le(other, set) == Qtrue) {
                return INT2NUM(1);
            }
        }
        else if (set_le(set, other) == Qtrue) {
            return INT2NUM(0);
        }
    }

    return Qnil;
}

Compares self and object.

If object is another set, returns:

-1, if self is a proper subset of object.
0, if self and object have the same elements.
1, if self is a proper superset of object.
nil, if none of the above; that is, if self and object each have one or more elements not included in the other.

Examples:

Example

set = Set[0, 1, 2]
set <=> Set[3, 2, 1, 0] # => -1
set <=> Set[2, 1, 0]    # => 0
set <=> Set[1, 0]       # => 1
set <=> Set[1, 0, 3]    # => nil

Returns nil if object is not a set:

Example

set <=> [2, 1, 0] # => nil  # Array, not Set.

Related: see Methods for Comparing.

See also #<= #== #<< #=== also in 4.0 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

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