Class: Symbol

Inherits:
Object show all
Includes:
Comparable
Defined in:
string.c

Overview

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

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Comparable

#<, #<=, #>, #>=, #between?

Class Method Details

.all_symbols ⇒ Array

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, :$=, :ThreadGroup,
                                :wait2, :$>]

Returns:




# File 'string.c'

VALUE
rb_sym_all_symbols(void)
{
    VALUE ary = rb_ary_new2(global_symbols.sym_id->num_entries);

    st_foreach(global_symbols.sym_id, symbols_i, ary);
    return ary;
}

Instance Method Details

#<=>(other) ⇒ -1, ...

Compares sym with other in string form.

Returns:

  • (-1, 0, +1, nil) 



# File 'string.c'

static VALUE
sym_cmp(VALUE sym, VALUE other)
{
if (!SYMBOL_P(other)) {
return Qnil;
}

#==(obj) ⇒ Boolean

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

Returns:

  • (Boolean) 



# File 'string.c'

static VALUE
sym_equal(VALUE sym1, VALUE sym2)
{
    if (sym1 == sym2) return Qtrue;
    return Qfalse;
}

#==(obj) ⇒ Boolean

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

Returns:

  • (Boolean) 



# File 'string.c'

static VALUE
sym_equal(VALUE sym1, VALUE sym2)
{
    if (sym1 == sym2) return Qtrue;
    return Qfalse;
}

#=~(obj) ⇒ Fixnum?

Returns sym.to_s =~ obj.

Returns:




# File 'string.c'

static VALUE
sym_match(VALUE sym, VALUE other)
{
    return rb_str_match(rb_sym_to_s(sym), other);
}

#[](idx) ⇒ String #[](b, n) ⇒ String

Returns sym.to_s[].

Overloads:




# File 'string.c'

static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
    return rb_str_aref_m(argc, argv, rb_sym_to_s(sym));
}

#capitalize ⇒ Object

Same as sym.to_s.capitalize.intern.




# File 'string.c'

static VALUE
sym_capitalize(VALUE sym)
{
    return rb_str_intern(rb_str_capitalize(rb_id2str(SYM2ID(sym))));
}

#casecmp(other) ⇒ -1, ...

Case-insensitive version of Symbol#<=>.

Returns:

  • (-1, 0, +1, nil) 



# File 'string.c'

static VALUE
sym_casecmp(VALUE sym, VALUE other)
{
if (!SYMBOL_P(other)) {
return Qnil;
}

#downcase ⇒ Object

Same as sym.to_s.downcase.intern.




# File 'string.c'

static VALUE
sym_downcase(VALUE sym)
{
    return rb_str_intern(rb_str_downcase(rb_id2str(SYM2ID(sym))));
}

#empty? ⇒ Boolean

Returns that sym is :"" or not.

Returns:

  • (Boolean) 



# File 'string.c'

static VALUE
sym_empty(VALUE sym)
{
    return rb_str_empty(rb_id2str(SYM2ID(sym)));
}

#encoding ⇒ Encoding

Returns the Encoding object that represents the encoding of sym.

Returns:




# File 'string.c'

static VALUE
sym_encoding(VALUE sym)
{
    return rb_obj_encoding(rb_id2str(SYM2ID(sym)));
}

#id2name ⇒ String #to_s ⇒ String

Returns the name or string corresponding to sym.

:fred.id2name   #=> "fred"

Overloads:




# File 'string.c'

VALUE
rb_sym_to_s(VALUE sym)
{
    ID id = SYM2ID(sym);

    return str_new3(rb_cString, rb_id2str(id));
}

#inspect ⇒ String

Returns the representation of sym as a symbol literal.

:fred.inspect   #=> ":fred"

Returns:




# File 'string.c'

static VALUE
sym_inspect(VALUE sym)
{
VALUE str;
ID id = SYM2ID(sym);
rb_encoding *enc;
const char *ptr;
long len;
char *dest;
rb_encoding *resenc = rb_default_internal_encoding();

if (resenc == NULL) resenc = rb_default_external_encoding();
sym = rb_id2str(id);
enc = STR_ENC_GET(sym);
ptr = RSTRING_PTR(sym);
len = RSTRING_LEN(sym);
if ((resenc != enc && !rb_str_is_ascii_only_p(sym)) || len != (long)strlen(ptr) ||
!rb_enc_symname_p(ptr, enc) || !sym_printable(ptr, ptr + len, enc)) {
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] = ':';
}

#to_sym ⇒ Object #intern ⇒ Object

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




# File 'string.c'

static VALUE
sym_to_sym(VALUE sym)
{
    return sym;
}

#length ⇒ Integer

Same as sym.to_s.length.

Returns:




# File 'string.c'

static VALUE
sym_length(VALUE sym)
{
    return rb_str_length(rb_id2str(SYM2ID(sym)));
}

#=~(obj) ⇒ Fixnum?

Returns sym.to_s =~ obj.

Returns:




# File 'string.c'

static VALUE
sym_match(VALUE sym, VALUE other)
{
    return rb_str_match(rb_sym_to_s(sym), other);
}

#succ ⇒ Object

Same as sym.to_s.succ.intern.




# File 'string.c'

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

#length ⇒ Integer

Same as sym.to_s.length.

Returns:




# File 'string.c'

static VALUE
sym_length(VALUE sym)
{
    return rb_str_length(rb_id2str(SYM2ID(sym)));
}

#[](idx) ⇒ String #[](b, n) ⇒ String

Returns sym.to_s[].

Overloads:




# File 'string.c'

static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
    return rb_str_aref_m(argc, argv, rb_sym_to_s(sym));
}

#succ ⇒ Object

Same as sym.to_s.succ.intern.




# File 'string.c'

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

#swapcase ⇒ Object

Same as sym.to_s.swapcase.intern.




# File 'string.c'

static VALUE
sym_swapcase(VALUE sym)
{
    return rb_str_intern(rb_str_swapcase(rb_id2str(SYM2ID(sym))));
}

#to_proc ⇒ Object

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

(1..3).collect(&:to_s)  #=> ["1", "2", "3"]




# File 'string.c'

static VALUE
sym_to_proc(VALUE sym)
{
static VALUE sym_proc_cache = Qfalse;
enum {SYM_PROC_CACHE_SIZE = 67}

#id2name ⇒ String #to_s ⇒ String

Returns the name or string corresponding to sym.

:fred.id2name   #=> "fred"

Overloads:




# File 'string.c'

VALUE
rb_sym_to_s(VALUE sym)
{
    ID id = SYM2ID(sym);

    return str_new3(rb_cString, rb_id2str(id));
}

#to_sym ⇒ Object #intern ⇒ Object

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




# File 'string.c'

static VALUE
sym_to_sym(VALUE sym)
{
    return sym;
}

#upcase ⇒ Object

Same as sym.to_s.upcase.intern.




# File 'string.c'

static VALUE
sym_upcase(VALUE sym)
{
    return rb_str_intern(rb_str_upcase(rb_id2str(SYM2ID(sym))));
}