class Symbol
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 $f3.object_id #=> 2514190
In Files
- string.c
Parent
Included Modules
Public Class Methods
Returns an array of all the symbols currently in Ruby's symbol table.
Symbol.all_symbols.size #=> 903 Symbol.all_symbols[1,20] #=> [:floor, :ARGV, :Binding, :symlink, :chown, :EOFError, :$;, :String, :LOCK_SH, :"setuid?", :$<, :default_proc, :compact, :extend, :Tms, :getwd, :$=, :ThreadGroup, :wait2, :$>]
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;
}
Public Instance Methods
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.
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));
}
Equality—If sym and obj are exactly the same symbol,
returns true.
#define sym_equal rb_obj_equal
Equality—If sym and obj are exactly the same symbol,
returns true.
#define sym_equal rb_obj_equal
Returns sym.to_s =~ obj.
static VALUE
sym_match(VALUE sym, VALUE other)
{
return rb_str_match(rb_sym2str(sym), other);
}
Returns sym.to_s[].
static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
return rb_str_aref_m(argc, argv, rb_sym2str(sym));
}
Same as sym.to_s.capitalize.intern.
static VALUE
sym_capitalize(VALUE sym)
{
return rb_str_intern(rb_str_capitalize(rb_sym2str(sym)));
}
Case-insensitive version of Symbol#<=>.
static VALUE
sym_casecmp(VALUE sym, VALUE other)
{
if (!SYMBOL_P(other)) {
return Qnil;
}
return rb_str_casecmp(rb_sym2str(sym), rb_sym2str(other));
}
Same as sym.to_s.downcase.intern.
static VALUE
sym_downcase(VALUE sym)
{
return rb_str_intern(rb_str_downcase(rb_sym2str(sym)));
}
Returns that sym is :“” or not.
static VALUE
sym_empty(VALUE sym)
{
return rb_str_empty(rb_sym2str(sym));
}
Returns the Encoding object that represents the encoding of sym.
static VALUE
sym_encoding(VALUE sym)
{
return rb_obj_encoding(rb_sym2str(sym));
}
Returns the name or string corresponding to sym.
:fred.id2name #=> "fred"
VALUE
rb_sym_to_s(VALUE sym)
{
return str_new_shared(rb_cString, rb_sym2str(sym));
}
Returns the representation of sym as a symbol literal.
:fred.inspect #=> ":fred"
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;
}
In general, to_sym returns the Symbol
corresponding to an object. As sym is already a symbol,
self is returned in this case.
static VALUE
sym_to_sym(VALUE sym)
{
return sym;
}
Same as sym.to_s.length.
static VALUE
sym_length(VALUE sym)
{
return rb_str_length(rb_sym2str(sym));
}
Returns sym.to_s =~ obj.
static VALUE
sym_match(VALUE sym, VALUE other)
{
return rb_str_match(rb_sym2str(sym), other);
}
Same as sym.to_s.succ.intern.
static VALUE
sym_succ(VALUE sym)
{
return rb_str_intern(rb_str_succ(rb_sym2str(sym)));
}
Same as sym.to_s.length.
static VALUE
sym_length(VALUE sym)
{
return rb_str_length(rb_sym2str(sym));
}
Returns sym.to_s[].
static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
return rb_str_aref_m(argc, argv, rb_sym2str(sym));
}
Same as sym.to_s.succ.intern.
static VALUE
sym_succ(VALUE sym)
{
return rb_str_intern(rb_str_succ(rb_sym2str(sym)));
}
Same as sym.to_s.swapcase.intern.
static VALUE
sym_swapcase(VALUE sym)
{
return rb_str_intern(rb_str_swapcase(rb_sym2str(sym)));
}
Returns a Proc object which respond to the given method by sym.
(1..3).collect(&:to_s) #=> ["1", "2", "3"]
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 the name or string corresponding to sym.
:fred.id2name #=> "fred"
VALUE
rb_sym_to_s(VALUE sym)
{
return str_new_shared(rb_cString, rb_sym2str(sym));
}
In general, to_sym returns the Symbol
corresponding to an object. As sym is already a symbol,
self is returned in this case.
static VALUE
sym_to_sym(VALUE sym)
{
return sym;
}
Same as sym.to_s.upcase.intern.
static VALUE
sym_upcase(VALUE sym)
{
return rb_str_intern(rb_str_upcase(rb_sym2str(sym)));
}