class Symbol

Parent:
Object
Included modules:
Comparable

Symbol objects represent names and some strings inside the Ruby interpreter. They are generated using the :name and :"string" literals syntax, and by the various to_sym methods. The same Symbol object will be created for a given name or string for the duration of a program's execution, regardless of the context or meaning of that name. Thus if Fred is a constant in one context, a method in another, and a class in a third, the Symbol :Fred will be the same object in all three contexts.

module One
  class Fred
  end
  $f1 = :Fred
end
module Two
  Fred = 1
  $f2 = :Fred
end
def Fred()
end
$f3 = :Fred
$f1.object_id   #=> 2514190
$f2.object_id   #=> 2514190
$f3.object_id   #=> 2514190

Public Class Methods

all_symbols → array Show source 
VALUE
rb_sym_all_symbols(void)
{
    VALUE ary = rb_ary_new2(global_symbols.str_sym->num_entries);
    st_foreach(global_symbols.str_sym, symbols_i, ary);
    return ary;
}

Returns an array of all the symbols currently in Ruby's symbol table.

Symbol.all_symbols.size    #=> 903
Symbol.all_symbols[1,20]   #=> [:floor, :ARGV, :Binding, :symlink,
                                :chown, :EOFError, :$;, :String,
                                :LOCK_SH, :"setuid?", :$<,
                                :default_proc, :compact, :extend,
                                :Tms, :getwd, :$=, :ThreadGroup,
                                :wait2, :$>]
json_create(o) Show source 
# File ext/json/lib/json/add/symbol.rb, line 21
def self.json_create(o)
  o['s'].to_sym
end

Deserializes JSON string by converting the string value stored in the object to a Symbol

Public Instance Methods

symbol <=> other_symbol → -1, 0, +1 or nil Show source 
static VALUE
sym_cmp(VALUE sym, VALUE other)
{
    if (!SYMBOL_P(other)) {
        return Qnil;
    }
    return rb_str_cmp_m(rb_sym2str(sym), rb_sym2str(other));
}

Compares symbol with other_symbol after calling to_s on each of the symbols. Returns -1, 0, +1 or nil depending on whether symbol is less than, equal to, or greater than other_symbol.

+nil+ is returned if the two values are incomparable.

See String#<=> for more information.

sym == obj → true or false Show source 
#define sym_equal rb_obj_equal

Equality—If sym and obj are exactly the same symbol, returns true.

sym == obj → true or false Show source 
#define sym_equal rb_obj_equal

Equality—If sym and obj are exactly the same symbol, returns true.

sym =~ obj → fixnum or nil Show source 
static VALUE
sym_match(VALUE sym, VALUE other)
{
    return rb_str_match(rb_sym2str(sym), other);
}

Returns sym.to_s =~ obj.

sym[idx] → char Show source
sym[b, n] → string 
static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
    return rb_str_aref_m(argc, argv, rb_sym2str(sym));
}

Returns sym.to_s[].

as_json(*) Show source 
# File ext/json/lib/json/add/symbol.rb, line 8
def as_json(*)
  {
    JSON.create_id => self.class.name,
    's'            => to_s,
  }
end

Returns a hash, that will be turned into a JSON object and represent this object.

capitalize → symbol Show source 
static VALUE
sym_capitalize(VALUE sym)
{
    return rb_str_intern(rb_str_capitalize(rb_sym2str(sym)));
}

Same as sym.to_s.capitalize.intern.

casecmp(other) → -1, 0, +1 or nil Show source 
static VALUE
sym_casecmp(VALUE sym, VALUE other)
{
    if (!SYMBOL_P(other)) {
        return Qnil;
    }
    return rb_str_casecmp(rb_sym2str(sym), rb_sym2str(other));
}

Case-insensitive version of Symbol#<=>.

dclone() Show source 
# File lib/rexml/xpath_parser.rb, line 17
def dclone ; self ; end

provides a unified clone operation, for REXML::XPathParser to use across multiple Object types

downcase → symbol Show source 
static VALUE
sym_downcase(VALUE sym)
{
    return rb_str_intern(rb_str_downcase(rb_sym2str(sym)));
}

Same as sym.to_s.downcase.intern.

empty? → true or false Show source 
static VALUE
sym_empty(VALUE sym)
{
    return rb_str_empty(rb_sym2str(sym));
}

Returns that sym is :“” or not.

encoding → encoding Show source 
static VALUE
sym_encoding(VALUE sym)
{
    return rb_obj_encoding(rb_sym2str(sym));
}

Returns the Encoding object that represents the encoding of sym.

id2name → string Show source 
VALUE
rb_sym_to_s(VALUE sym)
{
    return str_new_shared(rb_cString, rb_sym2str(sym));
}

Returns the name or string corresponding to sym.

:fred.id2name   #=> "fred"
:ginger.to_s    #=> "ginger"
inspect → string Show source 
static VALUE
sym_inspect(VALUE sym)
{
    VALUE str;
    const char *ptr;
    long len;
    char *dest;

    sym = rb_sym2str(sym);
    if (!rb_str_symname_p(sym)) {
        str = rb_str_inspect(sym);
        len = RSTRING_LEN(str);
        rb_str_resize(str, len + 1);
        dest = RSTRING_PTR(str);
        memmove(dest + 1, dest, len);
        dest[0] = ':';
    }
    else {
        rb_encoding *enc = STR_ENC_GET(sym);
        ptr = RSTRING_PTR(sym);
        len = RSTRING_LEN(sym);
        str = rb_enc_str_new(0, len + 1, enc);
        dest = RSTRING_PTR(str);
        dest[0] = ':';
        memcpy(dest + 1, ptr, len);
    }
    return str;
}

Returns the representation of sym as a symbol literal.

:fred.inspect   #=> ":fred"
intern → sym Show source 
static VALUE
sym_to_sym(VALUE sym)
{
    return sym;
}

In general, to_sym returns the Symbol corresponding to an object. As sym is already a symbol, self is returned in this case.

length → integer Show source 
static VALUE
sym_length(VALUE sym)
{
    return rb_str_length(rb_sym2str(sym));
}

Same as sym.to_s.length.

match(obj) → fixnum or nil Show source 
static VALUE
sym_match(VALUE sym, VALUE other)
{
    return rb_str_match(rb_sym2str(sym), other);
}

Returns sym.to_s =~ obj.

static VALUE
sym_succ(VALUE sym)
{
    return rb_str_intern(rb_str_succ(rb_sym2str(sym)));
}

Same as sym.to_s.succ.intern.

size → integer Show source 
static VALUE
sym_length(VALUE sym)
{
    return rb_str_length(rb_sym2str(sym));
}

Same as sym.to_s.length.

slice(idx) → char Show source
slice(b, n) → string 
static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
    return rb_str_aref_m(argc, argv, rb_sym2str(sym));
}

Returns sym.to_s[].

static VALUE
sym_succ(VALUE sym)
{
    return rb_str_intern(rb_str_succ(rb_sym2str(sym)));
}

Same as sym.to_s.succ.intern.

swapcase → symbol Show source 
static VALUE
sym_swapcase(VALUE sym)
{
    return rb_str_intern(rb_str_swapcase(rb_sym2str(sym)));
}

Same as sym.to_s.swapcase.intern.

to_json(*a) Show source 
# File ext/json/lib/json/add/symbol.rb, line 16
def to_json(*a)
  as_json.to_json(*a)
end

Stores class name (Symbol) with String representation of Symbol as a JSON string.

to_proc Show source 
static VALUE
sym_to_proc(VALUE sym)
{
    static VALUE sym_proc_cache = Qfalse;
    enum {SYM_PROC_CACHE_SIZE = 67};
    VALUE proc;
    long id, index;
    VALUE *aryp;

    if (!sym_proc_cache) {
        sym_proc_cache = rb_ary_tmp_new(SYM_PROC_CACHE_SIZE * 2);
        rb_gc_register_mark_object(sym_proc_cache);
        rb_ary_store(sym_proc_cache, SYM_PROC_CACHE_SIZE*2 - 1, Qnil);
    }

    id = SYM2ID(sym);
    index = (id % SYM_PROC_CACHE_SIZE) << 1;

    aryp = RARRAY_PTR(sym_proc_cache);
    if (aryp[index] == sym) {
        return aryp[index + 1];
    }
    else {
        proc = rb_proc_new(sym_call, (VALUE)id);
        rb_block_clear_env_self(proc);
        aryp[index] = sym;
        aryp[index + 1] = proc;
        return proc;
    }
}

Returns a Proc object which respond to the given method by sym.

(1..3).collect(&:to_s)  #=> ["1", "2", "3"]
to_s → string Show source 
VALUE
rb_sym_to_s(VALUE sym)
{
    return str_new_shared(rb_cString, rb_sym2str(sym));
}

Returns the name or string corresponding to sym.

:fred.id2name   #=> "fred"
:ginger.to_s    #=> "ginger"
to_sym → sym Show source 
static VALUE
sym_to_sym(VALUE sym)
{
    return sym;
}

In general, to_sym returns the Symbol corresponding to an object. As sym is already a symbol, self is returned in this case.

upcase → symbol Show source 
static VALUE
sym_upcase(VALUE sym)
{
    return rb_str_intern(rb_str_upcase(rb_sym2str(sym)));
}

Same as sym.to_s.upcase.intern.

Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.