Class: Struct

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain: self, `::Enumerable`
Inherits:	Object
Defined in:	struct.c, struct.c

Overview

Class Struct provides a convenient way to create a simple class that can store and fetch values.

This example creates a subclass of Struct, Struct::Customer; the first argument, a string, is the name of the subclass; the other arguments, symbols, determine the members of the new subclass.

Customer = Struct.new('Customer', :name, :address, :zip)
Customer.name       # => "Struct::Customer"
Customer.class      # => Class
Customer.superclass # => Struct

Corresponding to each member are two methods, a writer and a reader, that store and fetch values:

methods = Customer.instance_methods false
methods # => [:zip, :address=, :zip=, :address, :name, :name=]

An instance of the subclass may be created, and its members assigned values, via method .new:

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

The member values may be managed thus:

joe.name    # => "Joe Smith"
joe.name = 'Joseph Smith'
joe.name    # => "Joseph Smith"

And thus; note that member name may be expressed as either a string or a symbol:

joe[:name]  # => "Joseph Smith"
joe[:name] = 'Joseph Smith, Jr.'
joe['name'] # => "Joseph Smith, Jr."

See .new.

What’s Here

First, what’s elsewhere. Class Struct:

Inherits from class Object.
Includes module Enumerable, which provides dozens of additional methods.

See also ::Data, which is a somewhat similar, but stricter concept for defining immutable value objects.

Here, class Struct provides methods that are useful for:

Creating a Subclass
Querying
Comparing
Fetching
Assigning
Iterating
Converting

Methods for Creating a Struct Subclass

.new: Returns a new subclass of Struct.

Methods for Querying

#hash: Returns the integer hash code.
#size (aliased as #length): Returns the number of members.

Methods for Comparing

#==: Returns whether a given object is equal to self, using #== to compare member values.
#eql?: Returns whether a given object is equal to self, using #eql? to compare member values.

Methods for Fetching

#[]: Returns the value associated with a given member name.
#to_a (aliased as #values, #deconstruct): Returns the member values in self as an array.
#deconstruct_keys: Returns a hash of the name/value pairs for given member names.
#dig: Returns the object in nested objects that is specified by a given member name and additional arguments.
#members: Returns an array of the member names.
#select (aliased as #filter): Returns an array of member values from self, as selected by the given block.
#values_at: Returns an array containing values for given member names.

Methods for Assigning

#[]=: Assigns a given value to a given member name.

Methods for Iterating

#each: Calls a given block with each member name.
#each_pair: Calls a given block with each member name/value pair.

Methods for Converting

#inspect (aliased as #to_s): Returns a string representation of self.
#to_h: Returns a hash of the member name/value pairs in self.

Class Attribute Summary

StructClass.keyword_init? ⇒ Boolean readonly

Returns true if the class was initialized with keyword_init: true.

Class Method Summary

StructClass.members ⇒ array_of_symbols

Returns the member names of the Struct descendant as an array:
.new(*member_names, keyword_init: nil) {|Struct_subclass| ... } ⇒ Struct constructor

new returns a new subclass of Struct.

Instance Method Summary

#==(other) ⇒ Boolean

Returns true if and only if the following are true; otherwise returns false:
#[](name) ⇒ Object

Returns a value from self.
#[]=(name, value) ⇒ value

Assigns a value to a member.
#deconstruct ⇒ Array

Alias for #to_a.
#deconstruct_keys(array_of_names) ⇒ Hash

Returns a hash of the name/value pairs for the given member names.
#dig(name, *identifiers) ⇒ Object

Finds and returns an object among nested objects.
#each {|value| ... } ⇒ self

Calls the given block with the value of each member; returns self:
#each_pair {|(name, value)| ... } ⇒ self

Calls the given block with each member name/value pair; returns self:
#eql?(other) ⇒ Boolean

Returns true if and only if the following are true; otherwise returns false:
#select {|value| ... } ⇒ Array (also: #select)

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

Returns the integer hash value for self.
#initialize(*args) constructor
#inspect ⇒ String

Alias for #to_s.
#length ⇒ Integer (also: #size)

Returns the number of members.
#members ⇒ array_of_symbols

Returns the member names from self as an array:
#select {|value| ... } ⇒ Array

Alias for #filter.
#size ⇒ Integer

Alias for #length.
#to_a ⇒ Array (also: #values, #deconstruct)

Returns the values in self as an array:
#to_h ⇒ Hash

Returns a hash containing the name and value for each member:
#to_s ⇒ String (also: #inspect)

Returns a string representation of self:
#values ⇒ Array

Alias for #to_a.
#values_at(*integers) ⇒ Array

Returns an array of values from self.
#initialize_copy(s) Internal use only

`::Enumerable` - Included

#all?	Returns whether every element meets a given criterion.
#any?	Returns whether any element meets a given criterion.
#chain	Returns an enumerator object generated from this enumerator and given enumerables.
#chunk	Each element in the returned enumerator is a 2-element array consisting of:
#chunk_while	Creates an enumerator for each chunked elements.
#collect	Alias for Enumerable#map.
#collect_concat	Alias for Enumerable#flat_map.
#compact	Returns an array of all non-`nil` elements:
#count	Returns the count of elements, based on an argument or block criterion, if given.
#cycle	When called with positive integer argument `n` and a block, calls the block with each element, then does so again, until it has done so `n` times; returns `nil`:
#detect	Alias for Enumerable#find.
#drop	For positive integer `n`, returns an array containing all but the first `n` elements:
#drop_while	Calls the block with successive elements as long as the block returns a truthy value; returns an array of all elements after that point:
#each_cons	Calls the block with each successive overlapped `n`-tuple of elements; returns `self`:
#each_entry	Calls the given block with each element, converting multiple values from yield to an array; returns `self`:
#each_slice	Calls the block with each successive disjoint `n`-tuple of elements; returns `self`:
#each_with_index	Invoke `self.each` with `*args`.
#each_with_object	Calls the block once for each element, passing both the element and the given object:
#entries	Alias for Enumerable#to_a.
#filter	Returns an array containing elements selected by the block.
#filter_map	Returns an array containing truthy elements returned by the block.
#find	Returns the first element for which the block returns a truthy value.
#find_all	Alias for Enumerable#filter.
#find_index	Returns the index of the first element that meets a specified criterion, or `nil` if no such element is found.
#first	Returns the first element or elements.
#flat_map	Returns an array of flattened objects returned by the block.
#grep	Returns an array of objects based elements of `self` that match the given pattern.
#grep_v	Returns an array of objects based on elements of `self` that don’t match the given pattern.
#group_by	With a block given returns a hash:
#include?	Alias for Enumerable#member?.
#inject	Returns the result of applying a reducer to an initial value and the first element of the `::Enumerable`.
#lazy	Returns an `::Enumerator::Lazy`, which redefines most `::Enumerable` methods to postpone enumeration and enumerate values only on an as-needed basis.
#map	Returns an array of objects returned by the block.
#max	Returns the element with the maximum element according to a given criterion.
#max_by	Returns the elements for which the block returns the maximum values.
#member?	Returns whether for any element `object == element`:
#min	Returns the element with the minimum element according to a given criterion.
#min_by	Returns the elements for which the block returns the minimum values.
#minmax	Returns a 2-element array containing the minimum and maximum elements according to a given criterion.
#minmax_by	Returns a 2-element array containing the elements for which the block returns minimum and maximum values:
#none?	Returns whether no element meets a given criterion.
#one?	Returns whether exactly one element meets a given criterion.
#partition	With a block given, returns an array of two arrays:
#reduce	Alias for Enumerable#inject.
#reject	Returns an array of objects rejected by the block.
#reverse_each	With a block given, calls the block with each element, but in reverse order; returns `self`:
#select	Alias for Enumerable#filter.
#slice_after	Creates an enumerator for each chunked elements.
#slice_before	With argument `pattern`, returns an enumerator that uses the pattern to partition elements into arrays (“slices”).
#slice_when	Creates an enumerator for each chunked elements.
#sort	Returns an array containing the sorted elements of `self`.
#sort_by	With a block given, returns an array of elements of `self`, sorted according to the value returned by the block for each element.
#sum	With no block given, returns the sum of `initial_value` and the elements:
#take	For non-negative integer `n`, returns the first `n` elements:
#take_while	Calls the block with successive elements as long as the block returns a truthy value; returns an array of all elements up to that point:
#tally	When argument #hash is not given, returns a new hash whose keys are the distinct elements in `self`; each integer value is the count of occurrences of each element:
#to_a	Returns an array containing the items in `self`:
#to_h	When `self` consists of 2-element arrays, returns a hash each of whose entries is the key-value pair formed from one of those arrays:
#to_set	Makes a set from the enumerable object with given arguments.
#uniq	With no block, returns a new array containing only unique elements; the array has no two elements `e0` and `e1` such that `e0.eql?(e1)`:
#zip	With no block given, returns a new array `new_array` of size self.size whose elements are arrays.

Constructor Details

.new(member_names, keyword_init: nil) {|Struct_subclass| ... } ⇒ `Struct` .new(class_name, member_names, keyword_init: nil) {|Struct_subclass| ... } ⇒ `Struct` Struct_subclass.new(*member_names) ⇒ `Struct` Struct_subclass.new(**member_names) ⇒ `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, or via keyword arguments

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 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 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

# Initialization with keyword arguments:
Foo.new(foo: 0)         # => #<struct Struct::Foo foo=0, bar=nil>
Foo.new(foo: 0, bar: 1) # => #<struct Struct::Foo foo=0, bar=1>
Foo.new(foo: 0, bar: 1, baz: 2)
# Raises ArgumentError: unknown keywords: baz

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 can be both positional and keyword arguments.

Optional keyword argument keyword_init: allows to force only one type of arguments to be accepted:

KeywordsOnly = Struct.new(:foo, :bar, keyword_init: true)
KeywordsOnly.new(bar: 1, foo: 0)
# => #<struct KeywordsOnly foo=0, bar=1>
KeywordsOnly.new(0, 1)
# Raises ArgumentError: wrong number of arguments

PositionalOnly = Struct.new(:foo, :bar, keyword_init: false)
PositionalOnly.new(0, 1)
# => #<struct PositionalOnly foo=0, bar=1>
PositionalOnly.new(bar: 1, foo: 0)
# => #<struct PositionalOnly foo={:foo=>1, :bar=>2}, bar=nil>
# Note that no error is raised, but arguments treated as one hash value

# Same as not providing keyword_init:
Any = Struct.new(:foo, :bar, keyword_init: nil)
Any.new(foo: 1, bar: 2)
# => #<struct Any foo=1, bar=2>
Any.new(1, 2)
# => #<struct Any foo=1, bar=2>

[ GitHub ]

# File 'struct.c', line 641


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

    argc = rb_scan_args(argc, argv, "0*:", NULL, &opt);
    if (argc >= 1 && !SYMBOL_P(argv[0])) {
        name = argv[0];
        --argc;
        ++argv;
    }

    if (!NIL_P(opt)) {
        static ID keyword_ids[1];

        if (!keyword_ids[0]) {
            keyword_ids[0] = rb_intern("keyword_init");
        }
        rb_get_kwargs(opt, keyword_ids, 0, 1, &keyword_init);
        if (UNDEF_P(keyword_init)) {
            keyword_init = Qnil;
        }
        else if (RTEST(keyword_init)) {
            keyword_init = Qtrue;
        }
    }

    rest = rb_ident_hash_new();
    RBASIC_CLEAR_CLASS(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 (RTEST(rb_hash_has_key(rest, mem))) {
            rb_raise(rb_eArgError, "duplicate member: %"PRIsVALUE, mem);
        }
        rb_hash_aset(rest, mem, Qtrue);
    }
    rest = rb_hash_keys(rest);
    RBASIC_CLEAR_CLASS(rest);
    OBJ_FREEZE(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;
}

#initialize(*args)

[ GitHub ]

# File 'struct.c', line 740


static VALUE
rb_struct_initialize_m(int argc, const VALUE *argv, VALUE self)
{
    VALUE klass = rb_obj_class(self);
    rb_struct_modify(self);
    long n = num_members(klass);
    if (argc == 0) {
        rb_mem_clear((VALUE *)RSTRUCT_CONST_PTR(self), n);
        return Qnil;
    }

    bool keyword_init = false;
    switch (rb_struct_s_keyword_init(klass)) {
      default:
        if (argc > 1 || !RB_TYPE_P(argv[0], T_HASH)) {
            rb_error_arity(argc, 0, 0);
        }
        keyword_init = true;
        break;
      case Qfalse:
        break;
      case Qnil:
        if (argc > 1 || !RB_TYPE_P(argv[0], T_HASH)) {
            break;
        }
        keyword_init = rb_keyword_given_p();
        break;
    }
    if (keyword_init) {
        struct struct_hash_set_arg arg;
        rb_mem_clear((VALUE *)RSTRUCT_CONST_PTR(self), n);
        arg.self = self;
        arg.unknown_keywords = Qnil;
        rb_hash_foreach(argv[0], struct_hash_set_i, (VALUE)&arg);
        if (arg.unknown_keywords != Qnil) {
            rb_raise(rb_eArgError, "unknown keywords: %s",
                     RSTRING_PTR(rb_ary_join(arg.unknown_keywords, rb_str_new2(", "))));
        }
    }
    else {
        if (n < argc) {
            rb_raise(rb_eArgError, "struct size differs");
        }
        for (long i=0; i<argc; i++) {
            RSTRUCT_SET(self, i, argv[i]);
        }
        if (n > argc) {
            rb_mem_clear((VALUE *)RSTRUCT_CONST_PTR(self)+argc, n-argc);
        }
    }
    return Qnil;
}

Class Attribute Details

StructClass.keyword_init? ⇒ `Boolean` (readonly)

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

[ GitHub ]

# File 'struct.c', line 343


static VALUE
rb_struct_s_keyword_init_p(VALUE obj)
{
}

Class Method Details

StructClass.members ⇒ `array_of_symbols`

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

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

[ GitHub ]

# File 'struct.c', line 205


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

    return rb_ary_dup(members);
}

Instance Method Details

#==(other) ⇒ `Boolean`

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

[ GitHub ]

# File 'struct.c', line 1398


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);
}

#[](name) ⇒ Object #[](n) ⇒ Object

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@Array+Indexes:

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

Raises IndexError if n is out of range.

[ GitHub ]

# File 'struct.c', line 1216


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);
}

#[]=(name, value) ⇒ `value` #[]=(n, value) ⇒ `value`

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@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.

[ GitHub ]

# File 'struct.c', line 1254


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;
}

#to_a ⇒ Array #deconstruct ⇒ Array

Alias for #to_a.

#deconstruct_keys(array_of_names) ⇒ Hash

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}

[ GitHub ]

# File 'struct.c', line 1090


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;
}

#dig(name, identifiers) ⇒ Object #dig(n, identifiers) ⇒ Object

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

[ GitHub ]

# File 'struct.c', line 1542


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);
}

#each {|value| ... } ⇒ `self` #each ⇒ Enumerator

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.

[ GitHub ]

# File 'struct.c', line 890


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;
}

#each_pair {|(name, value)| ... } ⇒ `self` #each_pair ⇒ Enumerator

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.

[ GitHub ]

# File 'struct.c', line 925


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;
}

#eql?(other) ⇒ `Boolean`

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[:name] = 'Joe Smith, Jr.'
joe_jr.eql?(joe) # => false

Related: Object#==.

[ GitHub ]

# File 'struct.c', line 1479


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);
}

#select {|value| ... } ⇒ Array #select ⇒ Enumerator
Also known as: #select

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.

[ GitHub ]

# File 'struct.c', line 1346


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;
}

#hash ⇒ Integer

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 #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.

[ GitHub ]

# File 'struct.c', line 1430


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);
}

#initialize_copy(s)

This method is for internal use only.

[ GitHub ]

# File 'struct.c', line 1121


VALUE
rb_struct_init_copy(VALUE copy, VALUE s)
{
    long i, len;

    if (!OBJ_INIT_COPY(copy, s)) return copy;
    if (RSTRUCT_LEN(copy) != RSTRUCT_LEN(s)) {
        rb_raise(rb_eTypeError, "struct size mismatch");
    }

    for (i=0, len=RSTRUCT_LEN(copy); i<len; i++) {
        RSTRUCT_SET(copy, i, RSTRUCT_GET(s, i));
    }

    return copy;
}

#to_s ⇒ String #inspect ⇒ String

Alias for #to_s.

#length ⇒ Integer Also known as: #size

Returns the number of members.

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

[ GitHub ]

# File 'struct.c', line 1504


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

#members ⇒ `array_of_symbols`

Returns the member names from self as an array:

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

Related: #to_a.

[ GitHub ]

# File 'struct.c', line 225


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

#select {|value| ... } ⇒ Array #select ⇒ Enumerator

Alias for #filter.

#length ⇒ Integer #size ⇒ Integer

Alias for #length.

#to_a ⇒ Array Also known as: #values, #deconstruct

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]

Related: #members.

[ GitHub ]

# File 'struct.c', line 1026


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

#to_h ⇒ Hash #to_h {|name, value| ... } ⇒ Hash

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.

[ GitHub ]

# File 'struct.c', line 1055


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;
}

#to_s ⇒ String Also known as: #inspect

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>"

[ GitHub ]

# File 'struct.c', line 1007


static VALUE
rb_struct_inspect(VALUE s)
{
    return rb_exec_recursive(inspect_struct, s, rb_str_new2("#<struct "));
}

#to_a ⇒ Array #values ⇒ Array

Alias for #to_a.

#values_at(*integers) ⇒ Array #values_at(integer_range) ⇒ Array

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@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@Array+Indexes.

[ GitHub ]

# File 'struct.c', line 1322


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);
}

Class: Struct

Overview

What’s Here

Methods for Creating a Struct Subclass

Methods for Querying

Methods for Comparing

Methods for Fetching

Methods for Assigning

Methods for Iterating

Methods for Converting

Class Attribute Summary

Class Method Summary

Instance Method Summary

::Enumerable - Included

Constructor Details

.new(*member_names, keyword_init: nil) {|Struct_subclass| ... } ⇒ Struct .new(class_name, *member_names, keyword_init: nil) {|Struct_subclass| ... } ⇒ Struct Struct_subclass.new(*member_names) ⇒ Struct Struct_subclass.new(**member_names) ⇒ Struct

#initialize(*args)

Class Attribute Details

StructClass.keyword_init? ⇒ Boolean (readonly)

Class Method Details

StructClass.members ⇒ array_of_symbols

Instance Method Details

#==(other) ⇒ Boolean

#[](name) ⇒ Object #[](n) ⇒ Object

#[]=(name, value) ⇒ value #[]=(n, value) ⇒ value

#to_a ⇒ Array #deconstruct ⇒ Array

#deconstruct_keys(array_of_names) ⇒ Hash

#dig(name, *identifiers) ⇒ Object #dig(n, *identifiers) ⇒ Object

#each {|value| ... } ⇒ self #each ⇒ Enumerator

#each_pair {|(name, value)| ... } ⇒ self #each_pair ⇒ Enumerator

#eql?(other) ⇒ Boolean

#select {|value| ... } ⇒ Array #select ⇒ Enumerator Also known as: #select

#hash ⇒ Integer

#initialize_copy(s)

#to_s ⇒ String #inspect ⇒ String

#length ⇒ Integer Also known as: #size

#members ⇒ array_of_symbols

#select {|value| ... } ⇒ Array #select ⇒ Enumerator

#length ⇒ Integer #size ⇒ Integer

#to_a ⇒ Array Also known as: #values, #deconstruct

#to_h ⇒ Hash #to_h {|name, value| ... } ⇒ Hash

#to_s ⇒ String Also known as: #inspect

#to_a ⇒ Array #values ⇒ Array

#values_at(*integers) ⇒ Array #values_at(integer_range) ⇒ Array

`::Enumerable` - Included

.new(member_names, keyword_init: nil) {|Struct_subclass| ... } ⇒ `Struct` .new(class_name, member_names, keyword_init: nil) {|Struct_subclass| ... } ⇒ `Struct` Struct_subclass.new(*member_names) ⇒ `Struct` Struct_subclass.new(**member_names) ⇒ `Struct`

StructClass.keyword_init? ⇒ `Boolean` (readonly)

StructClass.members ⇒ `array_of_symbols`

#==(other) ⇒ `Boolean`

#[]=(name, value) ⇒ `value` #[]=(n, value) ⇒ `value`

#dig(name, identifiers) ⇒ Object #dig(n, identifiers) ⇒ Object

#each {|value| ... } ⇒ `self` #each ⇒ Enumerator

#each_pair {|(name, value)| ... } ⇒ `self` #each_pair ⇒ Enumerator

#eql?(other) ⇒ `Boolean`

#select {|value| ... } ⇒ Array #select ⇒ Enumerator
Also known as: #select

#members ⇒ `array_of_symbols`