class Struct

Returns true if the class was initialized with keyword_init: true. Otherwise returns nil or false.

Examples:

Foo = Struct.new(:a)
Foo.keyword_init? # => nil
Bar = Struct.new(:a, keyword_init: true)
Bar.keyword_init? # => true
Baz = Struct.new(:a, keyword_init: false)
Baz.keyword_init? # => false

static VALUE
rb_struct_s_keyword_init_p(VALUE obj)
{
}

Returns the member names of the Struct descendant as an array:

Customer = Struct.new(:name, :address, :zip)
Customer.members # => [:name, :address, :zip]

static VALUE
rb_struct_s_members_m(VALUE klass)
{
    VALUE members = rb_struct_s_members(klass);

    return rb_ary_dup(members);
}

Struct.new returns a new subclass of Struct. The new subclass:

• May be anonymous, or may have the name given by class_name.

• May have members as given by member_names.

• May have initialization via ordinary arguments (the default) or via keyword arguments (if keyword_init: true is given).

The new subclass has its own method ::new; thus:

Foo = Struct.new('Foo', :foo, :bar) # => Struct::Foo
f = Foo.new(0, 1)                   # => #<struct Struct::Foo foo=0, bar=1>

Class Name

With string argument class_name, returns a new subclass of Struct named Struct::class_name:

Foo = Struct.new('Foo', :foo, :bar) # => Struct::Foo
Foo.name                            # => "Struct::Foo"
Foo.superclass                      # => Struct

Without string argument class_name, returns a new anonymous subclass of Struct:

Struct.new(:foo, :bar).name # => nil

Block

With a block given, the created subclass is yielded to the block:

Customer = Struct.new('Customer', :name, :address) do |new_class|
  p "The new subclass is #{new_class}"
  def greeting
    "Hello #{name} at #{address}"
  end
end           # => Struct::Customer
dave = Customer.new('Dave', '123 Main')
dave # =>     #<struct Struct::Customer name="Dave", address="123 Main">
dave.greeting # => "Hello Dave at 123 Main"

Output, from Struct.new:

"The new subclass is Struct::Customer"

Member Names

Symbol arguments member_names determines the members of the new subclass:

Struct.new(:foo, :bar).members        # => [:foo, :bar]
Struct.new('Foo', :foo, :bar).members # => [:foo, :bar]

The new subclass has instance methods corresponding to member_names:

Foo = Struct.new('Foo', :foo, :bar)
Foo.instance_methods(false) # => [:foo, :bar, :foo=, :bar=]
f = Foo.new                 # => #<struct Struct::Foo foo=nil, bar=nil>
f.foo                       # => nil
f.foo = 0                   # => 0
f.bar                       # => nil
f.bar = 1                   # => 1
f                           # => #<struct Struct::Foo foo=0, bar=1>

Singleton Methods

A subclass returned by Struct.new has these singleton methods:

• Method ::new creates an instance of the subclass:

  Foo.new          # => #<struct Struct::Foo foo=nil, bar=nil>
  Foo.new(0)       # => #<struct Struct::Foo foo=0, bar=nil>
  Foo.new(0, 1)    # => #<struct Struct::Foo foo=0, bar=1>
  Foo.new(0, 1, 2) # Raises ArgumentError: struct size differs
  

  Method ::[] is an alias for method ::new.

• Method :inspect returns a string representation of the subclass:

  Foo.inspect
  # => "Struct::Foo"
  

• Method ::members returns an array of the member names:

  Foo.members # => [:foo, :bar]
  

Keyword Argument

By default, the arguments for initializing an instance of the new subclass are ordinary arguments (not keyword arguments). With optional keyword argument keyword_init: true, the new subclass is initialized with keyword arguments:

# Without keyword_init: true.
Foo = Struct.new('Foo', :foo, :bar)
Foo                     # => Struct::Foo
Foo.new(0, 1)           # => #<struct Struct::Foo foo=0, bar=1>
# With keyword_init: true.
Bar = Struct.new(:foo, :bar, keyword_init: true)
Bar # =>                # => Bar(keyword_init: true)
Bar.new(bar: 1, foo: 0) # => #<struct Bar foo=0, bar=1>

static VALUE
rb_struct_s_def(int argc, VALUE *argv, VALUE klass)
{
    VALUE name, rest, keyword_init = Qnil;
    long i;
    VALUE st;
    st_table *tbl;

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    name = argv[0];
    if (SYMBOL_P(name)) {
        name = Qnil;
    }
    else {
        --argc;
        ++argv;
    }

    if (RB_TYPE_P(argv[argc-1], T_HASH)) {
        static ID keyword_ids[1];

        if (!keyword_ids[0]) {
            keyword_ids[0] = rb_intern("keyword_init");
        }
        rb_get_kwargs(argv[argc-1], keyword_ids, 0, 1, &keyword_init);
        if (keyword_init == Qundef) {
            keyword_init = Qnil;
        }
        else if (RTEST(keyword_init)) {
            keyword_init = Qtrue;
        }
        --argc;
    }

    rest = rb_ident_hash_new();
    RBASIC_CLEAR_CLASS(rest);
    OBJ_WB_UNPROTECT(rest);
    tbl = RHASH_TBL_RAW(rest);
    for (i=0; i<argc; i++) {
        VALUE mem = rb_to_symbol(argv[i]);
        if (rb_is_attrset_sym(mem)) {
            rb_raise(rb_eArgError, "invalid struct member: %"PRIsVALUE, mem);
        }
        if (st_insert(tbl, mem, Qtrue)) {
            rb_raise(rb_eArgError, "duplicate member: %"PRIsVALUE, mem);
        }
    }
    rest = rb_hash_keys(rest);
    st_clear(tbl);
    RBASIC_CLEAR_CLASS(rest);
    OBJ_FREEZE_RAW(rest);
    if (NIL_P(name)) {
        st = anonymous_struct(klass);
    }
    else {
        st = new_struct(name, klass);
    }
    setup_struct(st, rest);
    rb_ivar_set(st, id_keyword_init, keyword_init);
    if (rb_block_given_p()) {
        rb_mod_module_eval(0, 0, st);
    }

    return st;
}

Returns true if and only if the following are true; otherwise returns false:

• other.class == self.class.

• For each member name name, other.name == self.name.

Examples:

Customer = Struct.new(:name, :address, :zip)
joe    = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe_jr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe_jr == joe # => true
joe_jr[:name] = 'Joe Smith, Jr.'
# => "Joe Smith, Jr."
joe_jr == joe # => false

static VALUE
rb_struct_equal(VALUE s, VALUE s2)
{
    if (s == s2) return Qtrue;
    if (!RB_TYPE_P(s2, T_STRUCT)) return Qfalse;
    if (rb_obj_class(s) != rb_obj_class(s2)) return Qfalse;
    if (RSTRUCT_LEN(s) != RSTRUCT_LEN(s2)) {
        rb_bug("inconsistent struct"); /* should never happen */
    }

    return rb_exec_recursive_paired(recursive_equal, s, s2, s2);
}

Returns a value from self.

With symbol or string argument name given, returns the value for the named member:

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe[:zip] # => 12345

Raises NameError if name is not the name of a member.

With integer argument n given, returns self.values[n] if n is in range; see Array Indexes:

joe[2]  # => 12345
joe[-2] # => "123 Maple, Anytown NC"

Raises IndexError if n is out of range.

VALUE
rb_struct_aref(VALUE s, VALUE idx)
{
    int i = rb_struct_pos(s, &idx);
    if (i < 0) invalid_struct_pos(s, idx);
    return RSTRUCT_GET(s, i);
}

Assigns a value to a member.

With symbol or string argument name given, assigns the given value to the named member; returns value:

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe[:zip] = 54321 # => 54321
joe # => #<struct Customer name="Joe Smith", address="123 Maple, Anytown NC", zip=54321>

Raises NameError if name is not the name of a member.

With integer argument n given, assigns the given value to the n-th member if n is in range; see Array Indexes:

joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe[2] = 54321           # => 54321
joe[-3] = 'Joseph Smith' # => "Joseph Smith"
joe # => #<struct Customer name="Joseph Smith", address="123 Maple, Anytown NC", zip=54321>

Raises IndexError if n is out of range.

VALUE
rb_struct_aset(VALUE s, VALUE idx, VALUE val)
{
    int i = rb_struct_pos(s, &idx);
    if (i < 0) invalid_struct_pos(s, idx);
    rb_struct_modify(s);
    RSTRUCT_SET(s, i, val);
    return val;
}

Returns a hash of the name/value pairs for the given member names.

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
h = joe.deconstruct_keys([:zip, :address])
h # => {:zip=>12345, :address=>"123 Maple, Anytown NC"}

Returns all names and values if array_of_names is nil:

h = joe.deconstruct_keys(nil)
h # => {:name=>"Joseph Smith, Jr.", :address=>"123 Maple, Anytown NC", :zip=>12345}

static VALUE
rb_struct_deconstruct_keys(VALUE s, VALUE keys)
{
    VALUE h;
    long i;

    if (NIL_P(keys)) {
        return rb_struct_to_h(s);
    }
    if (UNLIKELY(!RB_TYPE_P(keys, T_ARRAY))) {
        rb_raise(rb_eTypeError,
                 "wrong argument type %"PRIsVALUE" (expected Array or nil)",
                 rb_obj_class(keys));

    }
    if (RSTRUCT_LEN(s) < RARRAY_LEN(keys)) {
        return rb_hash_new_with_size(0);
    }
    h = rb_hash_new_with_size(RARRAY_LEN(keys));
    for (i=0; i<RARRAY_LEN(keys); i++) {
        VALUE key = RARRAY_AREF(keys, i);
        int i = rb_struct_pos(s, &key);
        if (i < 0) {
            return h;
        }
        rb_hash_aset(h, key, RSTRUCT_GET(s, i));
    }
    return h;
}

Finds and returns an object among nested objects. The nested objects may be instances of various classes. See Dig Methods.

Given symbol or string argument name, returns the object that is specified by name and identifiers:

Foo = Struct.new(:a)
f = Foo.new(Foo.new({b: [1, 2, 3]}))
f.dig(:a) # => #<struct Foo a={:b=>[1, 2, 3]}>
f.dig(:a, :a) # => {:b=>[1, 2, 3]}
f.dig(:a, :a, :b) # => [1, 2, 3]
f.dig(:a, :a, :b, 0) # => 1
f.dig(:b, 0) # => nil

Given integer argument n, returns the object that is specified by n and identifiers:

f.dig(0) # => #<struct Foo a={:b=>[1, 2, 3]}>
f.dig(0, 0) # => {:b=>[1, 2, 3]}
f.dig(0, 0, :b) # => [1, 2, 3]
f.dig(0, 0, :b, 0) # => 1
f.dig(:b, 0) # => nil

static VALUE
rb_struct_dig(int argc, VALUE *argv, VALUE self)
{
    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    self = rb_struct_lookup(self, *argv);
    if (!--argc) return self;
    ++argv;
    return rb_obj_dig(argc, argv, self, Qnil);
}

Calls the given block with the value of each member; returns self:

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe.each {|value| p value }

Output:

"Joe Smith"
"123 Maple, Anytown NC"
12345

Returns an Enumerator if no block is given.

Related: each_pair.

static VALUE
rb_struct_each(VALUE s)
{
    long i;

    RETURN_SIZED_ENUMERATOR(s, 0, 0, struct_enum_size);
    for (i=0; i<RSTRUCT_LEN(s); i++) {
        rb_yield(RSTRUCT_GET(s, i));
    }
    return s;
}

Calls the given block with each member name/value pair; returns self:

Customer = Struct.new(:name, :address, :zip) # => Customer
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe.each_pair {|(name, value)| p "#{name} => #{value}" }

Output:

"name => Joe Smith"
"address => 123 Maple, Anytown NC"
"zip => 12345"

Returns an Enumerator if no block is given.

Related: each.

static VALUE
rb_struct_each_pair(VALUE s)
{
    VALUE members;
    long i;

    RETURN_SIZED_ENUMERATOR(s, 0, 0, struct_enum_size);
    members = rb_struct_members(s);
    if (rb_block_pair_yield_optimizable()) {
        for (i=0; i<RSTRUCT_LEN(s); i++) {
            VALUE key = rb_ary_entry(members, i);
            VALUE value = RSTRUCT_GET(s, i);
            rb_yield_values(2, key, value);
        }
    }
    else {
        for (i=0; i<RSTRUCT_LEN(s); i++) {
            VALUE key = rb_ary_entry(members, i);
            VALUE value = RSTRUCT_GET(s, i);
            rb_yield(rb_assoc_new(key, value));
        }
    }
    return s;
}

Returns true if and only if the following are true; otherwise returns false:

• other.class == self.class.

• For each member name name, other.name.eql?(self.name).

  Customer = Struct.new(:name, :address, :zip) joe = Customer.new(“Joe Smith”, “123 Maple, Anytown NC”, 12345) joe_jr = Customer.new(“Joe Smith”, “123 Maple, Anytown NC”, 12345) joe_jr.eql?(joe) # => true joe_jr = ‘Joe Smith, Jr.’ joe_jr.eql?(joe) # => false

Related: Object#==.

static VALUE
rb_struct_eql(VALUE s, VALUE s2)
{
    if (s == s2) return Qtrue;
    if (!RB_TYPE_P(s2, T_STRUCT)) return Qfalse;
    if (rb_obj_class(s) != rb_obj_class(s2)) return Qfalse;
    if (RSTRUCT_LEN(s) != RSTRUCT_LEN(s2)) {
        rb_bug("inconsistent struct"); /* should never happen */
    }

    return rb_exec_recursive_paired(recursive_eql, s, s2, s2);
}

Returns the integer hash value for self.

Two structs of the same class and with the same content will have the same hash code (and will compare using Struct#eql?):

Customer = Struct.new(:name, :address, :zip)
joe    = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe_jr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe.hash == joe_jr.hash # => true
joe_jr[:name] = 'Joe Smith, Jr.'
joe.hash == joe_jr.hash # => false

Related: Object#hash.

static VALUE
rb_struct_hash(VALUE s)
{
    long i, len;
    st_index_t h;
    VALUE n;

    h = rb_hash_start(rb_hash(rb_obj_class(s)));
    len = RSTRUCT_LEN(s);
    for (i = 0; i < len; i++) {
        n = rb_hash(RSTRUCT_GET(s, i));
        h = rb_hash_uint(h, NUM2LONG(n));
    }
    h = rb_hash_end(h);
    return ST2FIX(h);
}

Returns a string representation of self:

Customer = Struct.new(:name, :address, :zip) # => Customer
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe.inspect # => "#<struct Customer name=\"Joe Smith\", address=\"123 Maple, Anytown NC\", zip=12345>"

Struct#to_s is an alias for Struct#inspect.

static VALUE
rb_struct_inspect(VALUE s)
{
    return rb_exec_recursive(inspect_struct, s, 0);
}

Returns the member names from self as an array:

Customer = Struct.new(:name, :address, :zip)
Customer.new.members # => [:name, :address, :zip]

Related: to_a.

static VALUE
rb_struct_members_m(VALUE obj)
{
    return rb_struct_s_members_m(rb_obj_class(obj));
}

With a block given, returns an array of values from self for which the block returns a truthy value:

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
a = joe.select {|value| value.is_a?(String) }
a # => ["Joe Smith", "123 Maple, Anytown NC"]
a = joe.select {|value| value.is_a?(Integer) }
a # => [12345]

With no block given, returns an Enumerator.

Struct#filter is an alias for Struct#select.

static VALUE
rb_struct_select(int argc, VALUE *argv, VALUE s)
{
    VALUE result;
    long i;

    rb_check_arity(argc, 0, 0);
    RETURN_SIZED_ENUMERATOR(s, 0, 0, struct_enum_size);
    result = rb_ary_new();
    for (i = 0; i < RSTRUCT_LEN(s); i++) {
        if (RTEST(rb_yield(RSTRUCT_GET(s, i)))) {
            rb_ary_push(result, RSTRUCT_GET(s, i));
        }
    }

    return result;
}

Returns the number of members.

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe.size #=> 3

Struct#length is an alias for Struct#size.

VALUE
rb_struct_size(VALUE s)
{
    return LONG2FIX(RSTRUCT_LEN(s));
}

Returns the values in self as an array:

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe.to_a # => ["Joe Smith", "123 Maple, Anytown NC", 12345]

Struct#values and Struct#deconstruct are aliases for Struct#to_a.

Related: members.

static VALUE
rb_struct_to_a(VALUE s)
{
    return rb_ary_new4(RSTRUCT_LEN(s), RSTRUCT_CONST_PTR(s));
}

Returns a hash containing the name and value for each member:

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
h = joe.to_h
h # => {:name=>"Joe Smith", :address=>"123 Maple, Anytown NC", :zip=>12345}

If a block is given, it is called with each name/value pair; the block should return a 2-element array whose elements will become a key/value pair in the returned hash:

h = joe.to_h{|name, value| [name.upcase, value.to_s.upcase]}
h # => {:NAME=>"JOE SMITH", :ADDRESS=>"123 MAPLE, ANYTOWN NC", :ZIP=>"12345"}

Raises ArgumentError if the block returns an inappropriate value.

static VALUE
rb_struct_to_h(VALUE s)
{
    VALUE h = rb_hash_new_with_size(RSTRUCT_LEN(s));
    VALUE members = rb_struct_members(s);
    long i;
    int block_given = rb_block_given_p();

    for (i=0; i<RSTRUCT_LEN(s); i++) {
        VALUE k = rb_ary_entry(members, i), v = RSTRUCT_GET(s, i);
        if (block_given)
            rb_hash_set_pair(h, rb_yield_values(2, k, v));
        else
            rb_hash_aset(h, k, v);
    }
    return h;
}

Returns an array of values from self.

With integer arguments integers given, returns an array containing each value given by one of integers:

Customer = Struct.new(:name, :address, :zip)
joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe.values_at(0, 2)    # => ["Joe Smith", 12345]
joe.values_at(2, 0)    # => [12345, "Joe Smith"]
joe.values_at(2, 1, 0) # => [12345, "123 Maple, Anytown NC", "Joe Smith"]
joe.values_at(0, -3)   # => ["Joe Smith", "Joe Smith"]

Raises IndexError if any of integers is out of range; see Array Indexes.

With integer range argument integer_range given, returns an array containing each value given by the elements of the range; fills with nil values for range elements larger than the structure:

joe.values_at(0..2)
# => ["Joe Smith", "123 Maple, Anytown NC", 12345]
joe.values_at(-3..-1)
# => ["Joe Smith", "123 Maple, Anytown NC", 12345]
joe.values_at(1..4) # => ["123 Maple, Anytown NC", 12345, nil, nil]

Raises RangeError if any element of the range is negative and out of range; see Array Indexes.

static VALUE
rb_struct_values_at(int argc, VALUE *argv, VALUE s)
{
    return rb_get_values_at(s, RSTRUCT_LEN(s), argc, argv, struct_entry);
}