Class Struct
In: struct.c
Parent: Object

A Struct is a convenient way to bundle a number of attributes together, using accessor methods, without having to write an explicit class.

The Struct class is a generator of specific classes, each one of which is defined to hold a set of variables and their accessors. In these examples, we‘ll call the generated class ``CustomerClass,’’ and we‘ll show an example instance of that class as ``CustomerInst.’‘

In the descriptions that follow, the parameter symbol refers to a symbol, which is either a quoted string or a Symbol (such as :name).

Methods

==   []   []=   each   each_pair   eql?   hash   inspect   length   members   new   new   select   size   to_a   to_s   values   values_at  

Included Modules

Enumerable

Public Class methods

[Source]

/*
 */

static VALUE
rb_struct_initialize(self, values)
    VALUE self, values;
{
    VALUE klass = rb_obj_class(self);
    VALUE size;
    long n;

    rb_struct_modify(self);
    size = rb_struct_iv_get(klass, "__size__");
    n = FIX2LONG(size);
    if (n < RARRAY(values)->len) {
        rb_raise(rb_eArgError, "struct size differs");
    }
    MEMCPY(RSTRUCT(self)->ptr, RARRAY(values)->ptr, VALUE, RARRAY(values)->len);
    if (n > RARRAY(values)->len) {
        rb_mem_clear(RSTRUCT(self)->ptr+RARRAY(values)->len,
                     n-RARRAY(values)->len);
    }
    return Qnil;
}

Creates a new class, named by aString, containing accessor methods for the given symbols. If the name aString is omitted, an anonymous structure class will be created. Otherwise, the name of this struct will appear as a constant in class Struct, so it must be unique for all Structs in the system and should start with a capital letter. Assigning a structure class to a constant effectively gives the class the name of the constant.

Struct::new returns a new Class object, which can then be used to create specific instances of the new structure. The number of actual parameters must be less than or equal to the number of attributes defined for this class; unset parameters default to \nil{}. Passing too many parameters will raise an \E{ArgumentError}.

The remaining methods listed in this section (class and instance) are defined for this generated class.

   # Create a structure with a name in Struct
   Struct.new("Customer", :name, :address)    #=> Struct::Customer
   Struct::Customer.new("Dave", "123 Main")   #=> #<Struct::Customer name="Dave", address="123 Main">

   # Create a structure named by its constant
   Customer = Struct.new(:name, :address)     #=> Customer
   Customer.new("Dave", "123 Main")           #=> #<Customer name="Dave", address="123 Main">

[Source]

/*
 *  call-seq:
 *     Struct.new( [aString] [, aSym]+> )    => StructClass
 *     StructClass.new(arg, ...)             => obj
 *     StructClass[arg, ...]                 => obj
 *
 *  Creates a new class, named by <i>aString</i>, containing accessor
 *  methods for the given symbols. If the name <i>aString</i> is
 *  omitted, an anonymous structure class will be created. Otherwise,
 *  the name of this struct will appear as a constant in class
 *  <code>Struct</code>, so it must be unique for all
 *  <code>Struct</code>s in the system and should start with a capital
 *  letter. Assigning a structure class to a constant effectively gives
 *  the class the name of the constant.
 *     
 *  <code>Struct::new</code> returns a new <code>Class</code> object,
 *  which can then be used to create specific instances of the new
 *  structure. The number of actual parameters must be
 *  less than or equal to the number of attributes defined for this
 *  class; unset parameters default to \nil{}.  Passing too many
 *  parameters will raise an \E{ArgumentError}.
 *
 *  The remaining methods listed in this section (class and instance)
 *  are defined for this generated class. 
 *     
 *     # Create a structure with a name in Struct
 *     Struct.new("Customer", :name, :address)    #=> Struct::Customer
 *     Struct::Customer.new("Dave", "123 Main")   #=> #<Struct::Customer name="Dave", address="123 Main">
 *     
 *     # Create a structure named by its constant
 *     Customer = Struct.new(:name, :address)     #=> Customer
 *     Customer.new("Dave", "123 Main")           #=> #<Customer name="Dave", address="123 Main">
 */

static VALUE
rb_struct_s_def(argc, argv, klass)
    int argc;
    VALUE *argv;
    VALUE klass;
{
    VALUE name, rest;
    long i;
    VALUE st;
    ID id;

    rb_scan_args(argc, argv, "1*", &name, &rest);
    if (!NIL_P(name) && SYMBOL_P(name)) {
        rb_ary_unshift(rest, name);
        name = Qnil;
    }
    for (i=0; i<RARRAY(rest)->len; i++) {
        id = rb_to_id(RARRAY(rest)->ptr[i]);
        RARRAY(rest)->ptr[i] = ID2SYM(id);
    }
    st = make_struct(name, rest, klass);
    if (rb_block_given_p()) {
        rb_mod_module_eval(0, 0, st);
    }

    return st;
}

Public Instance methods

Equality—Returns true if other_struct is equal to this one: they must be of the same class as generated by Struct::new, and the values of all instance variables must be equal (according to Object#==).

   Customer = Struct.new(:name, :address, :zip)
   joe   = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
   joejr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
   jane  = Customer.new("Jane Doe", "456 Elm, Anytown NC", 12345)
   joe == joejr   #=> true
   joe == jane    #=> false

[Source]

/*
 *  call-seq:
 *     struct == other_struct     => true or false
 *  
 *  Equality---Returns <code>true</code> if <i>other_struct</i> is
 *  equal to this one: they must be of the same class as generated by
 *  <code>Struct::new</code>, and the values of all instance variables
 *  must be equal (according to <code>Object#==</code>).
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe   = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joejr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     jane  = Customer.new("Jane Doe", "456 Elm, Anytown NC", 12345)
 *     joe == joejr   #=> true
 *     joe == jane    #=> false
 */

static VALUE
rb_struct_equal(s, s2)
    VALUE s, s2;
{
    long i;

    if (s == s2) return Qtrue;
    if (TYPE(s2) != T_STRUCT) return Qfalse;
    if (rb_obj_class(s) != rb_obj_class(s2)) return Qfalse;
    if (RSTRUCT(s)->len != RSTRUCT(s2)->len) {
        rb_bug("inconsistent struct"); /* should never happen */
    }

    for (i=0; i<RSTRUCT(s)->len; i++) {
        if (!rb_equal(RSTRUCT(s)->ptr[i], RSTRUCT(s2)->ptr[i])) return Qfalse;
    }
    return Qtrue;
}

Attribute Reference—Returns the value of the instance variable named by symbol, or indexed (0..length-1) by fixnum. Will raise NameError if the named variable does not exist, or IndexError if the index is out of range.

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

   joe["name"]   #=> "Joe Smith"
   joe[:name]    #=> "Joe Smith"
   joe[0]        #=> "Joe Smith"

[Source]

/*
 *  call-seq:
 *     struct[symbol]    => anObject
 *     struct[fixnum]    => anObject 
 *  
 *  Attribute Reference---Returns the value of the instance variable
 *  named by <i>symbol</i>, or indexed (0..length-1) by
 *  <i>fixnum</i>. Will raise <code>NameError</code> if the named
 *  variable does not exist, or <code>IndexError</code> if the index is
 *  out of range.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     
 *     joe["name"]   #=> "Joe Smith"
 *     joe[:name]    #=> "Joe Smith"
 *     joe[0]        #=> "Joe Smith"
 */

VALUE
rb_struct_aref(s, idx)
    VALUE s, idx;
{
    long i;

    if (TYPE(idx) == T_STRING || TYPE(idx) == T_SYMBOL) {
        return rb_struct_aref_id(s, rb_to_id(idx));
    }

    i = NUM2LONG(idx);
    if (i < 0) i = RSTRUCT(s)->len + i;
    if (i < 0)
        rb_raise(rb_eIndexError, "offset %ld too small for struct(size:%ld)",
                 i, RSTRUCT(s)->len);
    if (RSTRUCT(s)->len <= i)
        rb_raise(rb_eIndexError, "offset %ld too large for struct(size:%ld)",
                 i, RSTRUCT(s)->len);
    return RSTRUCT(s)->ptr[i];
}

Attribute Assignment—Assigns to the instance variable named by symbol or fixnum the value obj and returns it. Will raise a NameError if the named variable does not exist, or an IndexError if the index is out of range.

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

   joe["name"] = "Luke"
   joe[:zip]   = "90210"

   joe.name   #=> "Luke"
   joe.zip    #=> "90210"

[Source]

/*
 *  call-seq:
 *     struct[symbol] = obj    => obj
 *     struct[fixnum] = obj    => obj
 *  
 *  Attribute Assignment---Assigns to the instance variable named by
 *  <i>symbol</i> or <i>fixnum</i> the value <i>obj</i> and
 *  returns it. Will raise a <code>NameError</code> if the named
 *  variable does not exist, or an <code>IndexError</code> if the index
 *  is out of range.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     
 *     joe["name"] = "Luke"
 *     joe[:zip]   = "90210"
 *     
 *     joe.name   #=> "Luke"
 *     joe.zip    #=> "90210"
 */

VALUE
rb_struct_aset(s, idx, val)
    VALUE s, idx, val;
{
    long i;

    if (TYPE(idx) == T_STRING || TYPE(idx) == T_SYMBOL) {
        return rb_struct_aset_id(s, rb_to_id(idx), val);
    }

    i = NUM2LONG(idx);
    if (i < 0) i = RSTRUCT(s)->len + i;
    if (i < 0) {
        rb_raise(rb_eIndexError, "offset %ld too small for struct(size:%ld)",
                 i, RSTRUCT(s)->len);
    }
    if (RSTRUCT(s)->len <= i) {
        rb_raise(rb_eIndexError, "offset %ld too large for struct(size:%ld)",
                 i, RSTRUCT(s)->len);
    }
    rb_struct_modify(s);
    return RSTRUCT(s)->ptr[i] = val;
}

Calls block once for each instance variable, passing the value as a parameter.

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

produces:

   Joe Smith
   123 Maple, Anytown NC
   12345

[Source]

/*
 *  call-seq:
 *     struct.each {|obj| block }  => struct
 *  
 *  Calls <i>block</i> once for each instance variable, passing the
 *  value as a parameter.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe.each {|x| puts(x) }
 *     
 *  <em>produces:</em>
 *     
 *     Joe Smith
 *     123 Maple, Anytown NC
 *     12345
 */

static VALUE
rb_struct_each(s)
    VALUE s;
{
    long i;

    RETURN_ENUMERATOR(s, 0, 0);
    for (i=0; i<RSTRUCT(s)->len; i++) {
        rb_yield(RSTRUCT(s)->ptr[i]);
    }
    return s;
}

Calls block once for each instance variable, passing the name (as a symbol) and the value as parameters.

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

produces:

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

[Source]

/*
 *  call-seq:
 *     struct.each_pair {|sym, obj| block }     => struct
 *  
 *  Calls <i>block</i> once for each instance variable, passing the name
 *  (as a symbol) and the value as parameters.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe.each_pair {|name, value| puts("#{name} => #{value}") }
 *     
 *  <em>produces:</em>
 *     
 *     name => Joe Smith
 *     address => 123 Maple, Anytown NC
 *     zip => 12345
 */

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

    RETURN_ENUMERATOR(s, 0, 0);
    members = rb_struct_members(s);
    for (i=0; i<RSTRUCT(s)->len; i++) {
        rb_yield_values(2, rb_ary_entry(members, i), RSTRUCT(s)->ptr[i]);
    }
    return s;
}

code-seq:

  struct.eql?(other)   => true or false

Two structures are equal if they are the same object, or if all their fields are equal (using eql?).

[Source]

/*
 * code-seq:
 *   struct.eql?(other)   => true or false
 *
 * Two structures are equal if they are the same object, or if all their
 * fields are equal (using <code>eql?</code>).
 */

static VALUE
rb_struct_eql(s, s2)
    VALUE s, s2;
{
    long i;

    if (s == s2) return Qtrue;
    if (TYPE(s2) != T_STRUCT) return Qfalse;
    if (rb_obj_class(s) != rb_obj_class(s2)) return Qfalse;
    if (RSTRUCT(s)->len != RSTRUCT(s2)->len) {
        rb_bug("inconsistent struct"); /* should never happen */
    }

    for (i=0; i<RSTRUCT(s)->len; i++) {
        if (!rb_eql(RSTRUCT(s)->ptr[i], RSTRUCT(s2)->ptr[i])) return Qfalse;
    }
    return Qtrue;
}

Return a hash value based on this struct‘s contents.

[Source]

/*
 * call-seq:
 *   struct.hash   => fixnum
 *
 * Return a hash value based on this struct's contents.
 */

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

    h = rb_hash(rb_obj_class(s));
    for (i = 0; i < RSTRUCT(s)->len; i++) {
        h = (h << 1) | (h<0 ? 1 : 0);
        n = rb_hash(RSTRUCT(s)->ptr[i]);
        h ^= NUM2LONG(n);
    }
    return LONG2FIX(h);
}

Describe the contents of this struct in a string.

[Source]

/*
 * call-seq:
 *   struct.to_s      => string
 *   struct.inspect   => string
 *
 * Describe the contents of this struct in a string.
 */

static VALUE
rb_struct_inspect(s)
    VALUE s;
{
    if (rb_inspecting_p(s)) {
        const char *cname = rb_class2name(rb_obj_class(s));
        size_t len = strlen(cname) + 14;
        VALUE str = rb_str_new(0, len);

        snprintf(RSTRING(str)->ptr, len+1, "#<struct %s:...>", cname);
        RSTRING(str)->len = strlen(RSTRING(str)->ptr);
        return str;
    }
    return rb_protect_inspect(inspect_struct, s, 0);
}

Returns the number of instance variables.

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

[Source]

/*
 *  call-seq:
 *     struct.length    => fixnum
 *     struct.size      => fixnum
 *  
 *  Returns the number of instance variables.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe.length   #=> 3
 */

static VALUE
rb_struct_size(s)
    VALUE s;
{
    return LONG2FIX(RSTRUCT(s)->len);
}

Returns an array of strings representing the names of the instance variables.

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

[Source]

/*
 *  call-seq:
 *     struct.members    => array
 *  
 *  Returns an array of strings representing the names of the instance
 *  variables.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe.members   #=> ["name", "address", "zip"]
 */

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

Invokes the block passing in successive elements from struct, returning an array containing those elements for which the block returns a true value (equivalent to Enumerable#select).

   Lots = Struct.new(:a, :b, :c, :d, :e, :f)
   l = Lots.new(11, 22, 33, 44, 55, 66)
   l.select {|v| (v % 2).zero? }   #=> [22, 44, 66]

[Source]

/*
 *  call-seq:
 *     struct.select {|i| block }    => array
 *  
 *  Invokes the block passing in successive elements from
 *  <i>struct</i>, returning an array containing those elements
 *  for which the block returns a true value (equivalent to
 *  <code>Enumerable#select</code>).
 *     
 *     Lots = Struct.new(:a, :b, :c, :d, :e, :f)
 *     l = Lots.new(11, 22, 33, 44, 55, 66)
 *     l.select {|v| (v % 2).zero? }   #=> [22, 44, 66]
 */

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

    if (argc > 0) {
        rb_raise(rb_eArgError, "wrong number of arguments (%d for 0)", argc);
    }
    result = rb_ary_new();
    for (i = 0; i < RSTRUCT(s)->len; i++) {
        if (RTEST(rb_yield(RSTRUCT(s)->ptr[i]))) {
            rb_ary_push(result, RSTRUCT(s)->ptr[i]);
        }
    }

    return result;
}

Returns the number of instance variables.

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

[Source]

/*
 *  call-seq:
 *     struct.length    => fixnum
 *     struct.size      => fixnum
 *  
 *  Returns the number of instance variables.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe.length   #=> 3
 */

static VALUE
rb_struct_size(s)
    VALUE s;
{
    return LONG2FIX(RSTRUCT(s)->len);
}

Returns the values for this instance as an array.

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

[Source]

/*
 *  call-seq:
 *     struct.to_a     => array
 *     struct.values   => array
 *  
 *  Returns the values for this instance as an array.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe.to_a[1]   #=> "123 Maple, Anytown NC"
 */

static VALUE
rb_struct_to_a(s)
    VALUE s;
{
    return rb_ary_new4(RSTRUCT(s)->len, RSTRUCT(s)->ptr);
}

Describe the contents of this struct in a string.

[Source]

/*
 * call-seq:
 *   struct.to_s      => string
 *   struct.inspect   => string
 *
 * Describe the contents of this struct in a string.
 */

static VALUE
rb_struct_inspect(s)
    VALUE s;
{
    if (rb_inspecting_p(s)) {
        const char *cname = rb_class2name(rb_obj_class(s));
        size_t len = strlen(cname) + 14;
        VALUE str = rb_str_new(0, len);

        snprintf(RSTRING(str)->ptr, len+1, "#<struct %s:...>", cname);
        RSTRING(str)->len = strlen(RSTRING(str)->ptr);
        return str;
    }
    return rb_protect_inspect(inspect_struct, s, 0);
}

Returns the values for this instance as an array.

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

[Source]

/*
 *  call-seq:
 *     struct.to_a     => array
 *     struct.values   => array
 *  
 *  Returns the values for this instance as an array.
 *     
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe.to_a[1]   #=> "123 Maple, Anytown NC"
 */

static VALUE
rb_struct_to_a(s)
    VALUE s;
{
    return rb_ary_new4(RSTRUCT(s)->len, RSTRUCT(s)->ptr);
}

Returns an array containing the elements in self corresponding to the given selector(s). The selectors may be either integer indices or ranges. See also </code>.select<code>.

   a = %w{ a b c d e f }
   a.values_at(1, 3, 5)
   a.values_at(1, 3, 5, 7)
   a.values_at(-1, -3, -5, -7)
   a.values_at(1..3, 2...5)

[Source]

/* 
 * call-seq:
 *   struct.values_at(selector,... )  => an_array
 *
 *   Returns an array containing the elements in
 *   _self_ corresponding to the given selector(s). The selectors
 *   may be either integer indices or ranges. 
 *   See also </code>.select<code>.
 * 
 *      a = %w{ a b c d e f }
 *      a.values_at(1, 3, 5)
 *      a.values_at(1, 3, 5, 7)
 *      a.values_at(-1, -3, -5, -7)
 *      a.values_at(1..3, 2...5)
 */

static VALUE
rb_struct_values_at(argc, argv, s)
    int argc;
    VALUE *argv;
    VALUE s;
{
    return rb_values_at(s, RSTRUCT(s)->len, argc, argv, struct_entry);
}

[Validate]