Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://docs.ruby-lang.org/en/master/Struct.html below:

class Struct - Documentation for Ruby 3.5

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       
Customer.class      
Customer.superclass 

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

methods = Customer.instance_methods false
methods 

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 

The member values may be managed thus:

joe.name    
joe.name = 'Joseph Smith'
joe.name    

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

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

See Struct::new.

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 Struct Subclass

• Querying

• Comparing

• Fetching

• Assigning

• Iterating

• Converting

• ::new: Returns a new subclass of Struct.

• hash: Returns the integer hash code.

• size (aliased as length): Returns the number of members.

• ==: 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.

• []: 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.

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

• each: Calls a given block with each member name.

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

• inspect (aliased as to_s): Returns a string representation of self.

• to_h: Returns a hash of the member name/value pairs in self.

def self.json_create(object)
  new(*object['v'])
end

See as_json.

static VALUE
rb_struct_s_keyword_init_p(VALUE obj)
{
}

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

Examples:

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

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

    return rb_ary_dup(members);
}

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

Customer = Struct.new(:name, :address, :zip)
Customer.members 

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;
}

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) 
f = Foo.new(0, 1)                   

Class Name

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

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

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

Struct.new(:foo, :bar).name 

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           
dave = Customer.new('Dave', '123 Main')
dave 
dave.greeting 

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        
Struct.new('Foo', :foo, :bar).members 

The new subclass has instance methods corresponding to member_names:

Foo = Struct.new('Foo', :foo, :bar)
Foo.instance_methods(false) 
f = Foo.new                 
f.foo                       
f.foo = 0                   
f.bar                       
f.bar = 1                   
f                           

Singleton Methods

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

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

  Foo.new          
  Foo.new(0)       
  Foo.new(0, 1)    
  Foo.new(0, 1, 2) 
  
  
  Foo.new(foo: 0)         
  Foo.new(foo: 0, bar: 1) 
  Foo.new(foo: 0, bar: 1, baz: 2)
  
  

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

  Foo.inspect
  
  

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

  Foo.members 
  

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)

KeywordsOnly.new(0, 1)


PositionalOnly = Struct.new(:foo, :bar, keyword_init: false)
PositionalOnly.new(0, 1)

PositionalOnly.new(bar: 1, foo: 0)




Any = Struct.new(:foo, :bar, keyword_init: nil)
Any.new(foo: 1, bar: 2)

Any.new(1, 2)

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 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 
joe_jr[:name] = 'Joe Smith, Jr.'

joe_jr == joe 

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);
}

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] 

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 at Array:

joe[2]  
joe[-2] 

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;
}

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 
joe 

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 at Array:

joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
joe[2] = 54321           
joe[-3] = 'Joseph Smith' 
joe 

Raises IndexError if n is out of range.

def as_json(*)
  klass = self.class.name
  klass.to_s.empty? and raise JSON::JSONError, "Only named structs are supported!"
  {
    JSON.create_id => klass,
    'v'            => values,
  }
end

Methods Struct#as_json and Struct.json_create may be used to serialize and deserialize a Struct object; see Marshal.

Method Struct#as_json serializes self, returning a 2-element hash representing self:

require 'json/add/struct'
Customer = Struct.new('Customer', :name, :address, :zip)
x = Struct::Customer.new.as_json

Method JSON.create deserializes such a hash, returning a Struct object:

Struct::Customer.json_create(x)

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;
}

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 

Returns all names and values if array_of_names is nil:

h = joe.deconstruct_keys(nil)
h 

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);
}

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) 
f.dig(:a, :a) 
f.dig(:a, :a, :b) 
f.dig(:a, :a, :b, 0) 
f.dig(:b, 0) 

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

f.dig(0) 
f.dig(0, 0) 
f.dig(0, 0, :b) 
f.dig(0, 0, :b, 0) 
f.dig(:b, 0) 

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 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_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;
}

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

Customer = Struct.new(:name, :address, :zip) 
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_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 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) 
  joe_jr[:name] = 'Joe Smith, Jr.'
  joe_jr.eql?(joe) 
  

Related: Object#==.

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 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 
joe_jr[:name] = 'Joe Smith, Jr.'
joe.hash == joe_jr.hash 

Related: Object#hash.

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

Returns a string representation of self:

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

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

Returns the member names from self as an array:

Customer = Struct.new(:name, :address, :zip)
Customer.new.members 

Related: to_a.

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;
}

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 
a = joe.select {|value| value.is_a?(Integer) }
a 

With no block given, returns an Enumerator.

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

Returns the number of members.

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

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

Related: members.

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 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 

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 

Raises ArgumentError if the block returns an inappropriate value.

def to_json(*args)
  as_json.to_json(*args)
end

Returns a JSON string representing self:

require 'json/add/struct'
Customer = Struct.new('Customer', :name, :address, :zip)
puts Struct::Customer.new.to_json

Output:

{"json_class":"Struct","t":{'name':'Rowdy',"age":null}}

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);
}

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.values_at(2, 0)    
joe.values_at(2, 1, 0) 
joe.values_at(0, -3)   

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

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.values_at(-3..-1)

joe.values_at(1..4) 

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

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4