End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →
class method
Hash.[]
Hash[] → new_empty_hash
Hash[hash] → new_hash
Hash[ [*2_element_arrays] ] → new_hash
Hash[*objects] → new_hash
hash.c
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static VALUE
rb_hash_s_create(int argc, VALUE *argv, VALUE klass)
{
VALUE hash, tmp;
if (argc == 1) {
tmp = rb_hash_s_try_convert(Qnil, argv[0]);
if (!NIL_P(tmp)) {
hash = hash_alloc(klass);
hash_copy(hash, tmp);
return hash;
}
tmp = rb_check_array_type(argv[0]);
if (!NIL_P(tmp)) {
long i;
hash = hash_alloc(klass);
for (i = 0; i < RARRAY_LEN(tmp); ++i) {
VALUE e = RARRAY_AREF(tmp, i);
VALUE v = rb_check_array_type(e);
VALUE key, val = Qnil;
if (NIL_P(v)) {
rb_raise(rb_eArgError, "wrong element type %s at %ld (expected array)",
rb_builtin_class_name(e), i);
}
switch (RARRAY_LEN(v)) {
default:
rb_raise(rb_eArgError, "invalid number of elements (%ld for 1..2)",
RARRAY_LEN(v));
case 2:
val = RARRAY_AREF(v, 1);
case 1:
key = RARRAY_AREF(v, 0);
rb_hash_aset(hash, key, val);
}
}
return hash;
}
}
if (argc % 2 != 0) {
rb_raise(rb_eArgError, "odd number of arguments for Hash");
}
hash = hash_alloc(klass);
rb_hash_bulk_insert(argc, argv, hash);
hash_verify(hash);
return hash;
}
Returns a new Hash object populated with the given objects, if any. See Hash::new.
With no argument, returns a new empty Hash.
When the single given argument is a Hash, returns a new Hash populated with the entries from the given Hash, excluding the default value or proc.
Example
h = {foo: 0, bar: 1, baz: 2} Hash[h] # => {:foo=>0, :bar=>1, :baz=>2}
When the single given argument is an Array of 2-element Arrays, returns a new Hash object wherein each 2-element array forms a key-value entry:
Example
Hash[ [ [:foo, 0], [:bar, 1] ] ] # => {:foo=>0, :bar=>1}
When the argument count is an even number; returns a new Hash object wherein each successive pair of arguments has become a key-value entry:
Example
Hash[:foo, 0, :bar, 1] # => {:foo=>0, :bar=>1}
Raises an exception if the argument list does not conform to any of the above.