class Symbol
Symbol objects represent names 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 $f3.object_id #=> 2514190
Public Class Methods
Returns an array of all the symbols currently in Ruby's symbol table.
Symbol.all_symbols.size #=> 903
Symbol.all_symbols[1,20] #=> [:floor, :ARGV, :Binding, :symlink,
:chown, :EOFError, :$;, :String,
:LOCK_SH, :"setuid?", :$<,
:default_proc, :compact, :extend,
:Tms, :getwd, :$=, :ThreadGroup,
:wait2, :$>]
static VALUE
sym_all_symbols(VALUE _)
{
return rb_sym_all_symbols();
}
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));
}
Returns a hash, that will be turned into a JSON object and represent this object.
# File ext/json/lib/json/add/symbol.rb, line 9 def as_json(*) { JSON.create_id => self.class.name, 's' => to_s, } end
Same as sym.to_s.capitalize.intern.
static VALUE
sym_capitalize(int argc, VALUE *argv, VALUE sym)
{
return rb_str_intern(rb_str_capitalize(argc, argv, rb_sym2str(sym)));
}
Case-insensitive version of Symbol#<=>. Currently, case-insensitivity only works on characters A-Z/a-z, not all of Unicode. This is different from Symbol#casecmp?.
:aBcDeF.casecmp(:abcde) #=> 1 :aBcDeF.casecmp(:abcdef) #=> 0 :aBcDeF.casecmp(:abcdefg) #=> -1 :abcdef.casecmp(:ABCDEF) #=> 0
nil is returned if the two symbols have incompatible encodings, or if other_symbol is not a symbol.
:foo.casecmp(2) #=> nil "\u{e4 f6 fc}".encode("ISO-8859-1").to_sym.casecmp(:"\u{c4 d6 dc}") #=> nil
static VALUE
sym_casecmp(VALUE sym, VALUE other)
{
if (!SYMBOL_P(other)) {
return Qnil;
}
return str_casecmp(rb_sym2str(sym), rb_sym2str(other));
}
Returns true if sym and other_symbol are equal after Unicode case folding, false if they are not equal.
:aBcDeF.casecmp?(:abcde) #=> false :aBcDeF.casecmp?(:abcdef) #=> true :aBcDeF.casecmp?(:abcdefg) #=> false :abcdef.casecmp?(:ABCDEF) #=> true :"\u{e4 f6 fc}".casecmp?(:"\u{c4 d6 dc}") #=> true
nil is returned if the two symbols have incompatible encodings, or if other_symbol is not a symbol.
:foo.casecmp?(2) #=> nil "\u{e4 f6 fc}".encode("ISO-8859-1").to_sym.casecmp?(:"\u{c4 d6 dc}") #=> nil
static VALUE
sym_casecmp_p(VALUE sym, VALUE other)
{
if (!SYMBOL_P(other)) {
return Qnil;
}
return str_casecmp_p(rb_sym2str(sym), rb_sym2str(other));
}
provides a unified clone operation, for REXML::XPathParser to use across multiple Object types
# File lib/rexml/xpath_parser.rb, line 20 def dclone ; self ; end
Same as sym.to_s.downcase.intern.
static VALUE
sym_downcase(int argc, VALUE *argv, VALUE sym)
{
return rb_str_intern(rb_str_downcase(argc, argv, rb_sym2str(sym)));
}
Returns whether 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 true if sym ends with one of the suffixes given.
:hello.end_with?("ello") #=> true # returns true if one of the +suffixes+ matches. :hello.end_with?("heaven", "ello") #=> true :hello.end_with?("heaven", "paradise") #=> false
static VALUE
sym_end_with(int argc, VALUE *argv, VALUE sym)
{
return rb_str_end_with(argc, argv, rb_sym2str(sym));
}
Returns the name or string corresponding to sym.
:fred.id2name #=> "fred" :ginger.to_s #=> "ginger"
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 = rb_sym2str(sym);
const char *ptr;
long len;
char *dest;
if (!rb_str_symname_p(str)) {
str = rb_str_inspect(str);
len = RSTRING_LEN(str);
rb_str_resize(str, len + 1);
dest = RSTRING_PTR(str);
memmove(dest + 1, dest, len);
}
else {
rb_encoding *enc = STR_ENC_GET(str);
RSTRING_GETMEM(str, ptr, len);
str = rb_enc_str_new(0, len + 1, enc);
dest = RSTRING_PTR(str);
memcpy(dest + 1, ptr, len);
}
dest[0] = ':';
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.match.
static VALUE
sym_match_m(int argc, VALUE *argv, VALUE sym)
{
return rb_str_match_m(argc, argv, rb_sym2str(sym));
}
Returns sym.to_s.match?.
static VALUE
sym_match_m_p(int argc, VALUE *argv, VALUE sym)
{
return rb_str_match_m_p(argc, argv, 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.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));
}
Returns true if sym starts with one of the prefixes given. Each of the prefixes should be a String or a Regexp.
:hello.start_with?("hell") #=> true :hello.start_with?(/H/i) #=> true # returns true if one of the prefixes matches. :hello.start_with?("heaven", "hell") #=> true :hello.start_with?("heaven", "paradise") #=> false
static VALUE
sym_start_with(int argc, VALUE *argv, VALUE sym)
{
return rb_str_start_with(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(int argc, VALUE *argv, VALUE sym)
{
return rb_str_intern(rb_str_swapcase(argc, argv, rb_sym2str(sym)));
}
Returns a Proc object which responds to the given method by sym.
(1..3).collect(&:to_s) #=> ["1", "2", "3"]
VALUE
rb_sym_to_proc(VALUE sym)
{
}
Returns the name or string corresponding to sym.
:fred.id2name #=> "fred" :ginger.to_s #=> "ginger"
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(int argc, VALUE *argv, VALUE sym)
{
return rb_str_intern(rb_str_upcase(argc, argv, rb_sym2str(sym)));
}