In Files

  • string.c

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

Public Class Methods

all_symbols => array click to toggle source

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.sym_id->num_entries);

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

Public Instance Methods

<=>(p1) click to toggle source 
 
               static VALUE
sym_cmp(VALUE sym, VALUE other)
{
    if (!SYMBOL_P(other)) {
        return Qnil;
    }
    return rb_str_cmp_m(rb_sym_to_s(sym), rb_sym_to_s(other));
}
sym == obj => true or false click to toggle source

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

 
               static VALUE
sym_equal(VALUE sym1, VALUE sym2)
{
    if (sym1 == sym2) return Qtrue;
    return Qfalse;
}
sym == obj => true or false click to toggle source

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

 
               static VALUE
sym_equal(VALUE sym1, VALUE sym2)
{
    if (sym1 == sym2) return Qtrue;
    return Qfalse;
}
=~(p1) click to toggle source 
 
               static VALUE
sym_match(VALUE sym, VALUE other)
{
    return rb_str_match(rb_sym_to_s(sym), other);
}
[](*args) click to toggle source 
 
               static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
    return rb_str_aref_m(argc, argv, rb_sym_to_s(sym));
}
capitalize() click to toggle source 
 
               static VALUE
sym_capitalize(VALUE sym)
{
    return rb_str_intern(rb_str_capitalize(rb_id2str(SYM2ID(sym))));
}
casecmp(p1) click to toggle source 
 
               static VALUE
sym_casecmp(VALUE sym, VALUE other)
{
    if (!SYMBOL_P(other)) {
        return Qnil;
    }
    return rb_str_casecmp(rb_sym_to_s(sym), rb_sym_to_s(other));
}
downcase() click to toggle source 
 
               static VALUE
sym_downcase(VALUE sym)
{
    return rb_str_intern(rb_str_downcase(rb_id2str(SYM2ID(sym))));
}
empty?() click to toggle source 
 
               static VALUE
sym_empty(VALUE sym)
{
    return rb_str_empty(rb_id2str(SYM2ID(sym)));
}
encoding() click to toggle source 
 
               static VALUE
sym_encoding(VALUE sym)
{
    return rb_obj_encoding(rb_id2str(SYM2ID(sym)));
}
id2name => string click to toggle source

Returns the name or string corresponding to sym.

:fred.id2name   #=> "fred"

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

    return str_new3(rb_cString, rb_id2str(id));
}
inspect => string click to toggle source

Returns the representation of sym as a symbol literal.

:fred.inspect   #=> ":fred"

 
               static VALUE
sym_inspect(VALUE sym)
{
    VALUE str;
    ID id = SYM2ID(sym);
    rb_encoding *enc;

    sym = rb_id2str(id);
    enc = STR_ENC_GET(sym);
    str = rb_enc_str_new(0, RSTRING_LEN(sym)+1, enc);
    RSTRING_PTR(str)[0] = ':';
    memcpy(RSTRING_PTR(str)+1, RSTRING_PTR(sym), RSTRING_LEN(sym));
    if (RSTRING_LEN(sym) != strlen(RSTRING_PTR(sym)) ||
        !rb_enc_symname_p(RSTRING_PTR(sym), enc) ||
        !sym_printable(RSTRING_PTR(sym), RSTRING_END(sym), enc)) {
        str = rb_str_inspect(str);
        strncpy(RSTRING_PTR(str), ":\"", 2);
    }
    return str;
}
intern => sym click to toggle source

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;
}
length() click to toggle source 
 
               static VALUE
sym_length(VALUE sym)
{
    return rb_str_length(rb_id2str(SYM2ID(sym)));
}
match(p1) click to toggle source 
 
               static VALUE
sym_match(VALUE sym, VALUE other)
{
    return rb_str_match(rb_sym_to_s(sym), other);
}
next() click to toggle source 
 
               static VALUE
sym_succ(VALUE sym)
{
    return rb_str_intern(rb_str_succ(rb_sym_to_s(sym)));
}
size() click to toggle source 
 
               static VALUE
sym_length(VALUE sym)
{
    return rb_str_length(rb_id2str(SYM2ID(sym)));
}
slice(*args) click to toggle source 
 
               static VALUE
sym_aref(int argc, VALUE *argv, VALUE sym)
{
    return rb_str_aref_m(argc, argv, rb_sym_to_s(sym));
}
succ() click to toggle source 
 
               static VALUE
sym_succ(VALUE sym)
{
    return rb_str_intern(rb_str_succ(rb_sym_to_s(sym)));
}
swapcase() click to toggle source 
 
               static VALUE
sym_swapcase(VALUE sym)
{
    return rb_str_intern(rb_str_swapcase(rb_id2str(SYM2ID(sym))));
}
to_proc click to toggle source

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)
{
    return rb_proc_new(sym_call, (VALUE)SYM2ID(sym));
}
to_s => string click to toggle source

Returns the name or string corresponding to sym.

:fred.id2name   #=> "fred"

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

    return str_new3(rb_cString, rb_id2str(id));
}
to_sym => sym click to toggle source

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;
}
upcase() click to toggle source 
 
               static VALUE
sym_upcase(VALUE sym)
{
    return rb_str_intern(rb_str_upcase(rb_id2str(SYM2ID(sym))));
}