method

[]

v1_8_7_330 - Show latest stable - 2 notes - Class: Hash

[](...) public

Creates a new hash populated with the given objects. Equivalent to the literal { key, value, … }. Keys and values occur in pairs, so there must be an even number of arguments.

Hash["a", 100, "b", 200]       #=> {"a"=>100, "b"=>200}
Hash["a" => 100, "b" => 200]   #=> {"a"=>100, "b"=>200}
{ "a" => 100, "b" => 200 }     #=> {"a"=>100, "b"=>200}

Show source

/*
 *  call-seq:
 *     Hash[ [key =>|, value]* ]   => hash
 *
 *  Creates a new hash populated with the given objects. Equivalent to
 *  the literal <code>{ <i>key</i>, <i>value</i>, ... }</code>. Keys and
 *  values occur in pairs, so there must be an even number of arguments.
 *
 *     Hash["a", 100, "b", 200]       #=> {"a"=>100, "b"=>200}
 *     Hash["a" => 100, "b" => 200]   #=> {"a"=>100, "b"=>200}
 *     { "a" => 100, "b" => 200 }     #=> {"a"=>100, "b"=>200}
 */

static VALUE
rb_hash_s_create(argc, argv, klass)
    int argc;
    VALUE *argv;
    VALUE klass;
{
    VALUE hash, tmp;
    int i;

    if (argc == 1) {
        tmp = rb_check_convert_type(argv[0], T_HASH, "Hash", "to_hash");
        if (!NIL_P(tmp)) {
            hash = hash_alloc0(klass);
            RHASH(hash)->tbl = st_copy(RHASH(tmp)->tbl);
            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 v = rb_check_array_type(RARRAY_PTR(tmp)[i]);
                VALUE key, val = Qnil;

                if (NIL_P(v)) continue;
                switch (RARRAY_LEN(v)) {
                  case 2:
                    val = RARRAY_PTR(v)[1];
                  case 1:
                    key = RARRAY_PTR(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);
    for (i=0; i<argc; i+=2) {
        rb_hash_aset(hash, argv[i], argv[i + 1]);
    }

    return hash;
}

July 19, 2012

0 thanks

Assignment using 'key: value'

Another shorthand way of assigning key, value pairs:

Hash[one: 1, two: 2] #=> {:one=>1, :two=>2}

April 17, 2013

0 thanks

@UnfalseIdeas

What is the purpose of

Hash[one: 1, two: 1]

When you can write

{one: 1, two: 2}

Aren’t you just passing a hash into the [] method?

[]

Related methods

Assignment using 'key: value'

@UnfalseIdeas