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 $f3.object_id #=> 2514190
Returns an array of all the symbols currently in Ruby's symbol table.
Symbol.all_symbols.size #=> 903 Symbol.all_symbols[1,20] #=> [:floor, :ARGV, :Binding, :symlink, :chown, :EOFError, :$;, :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; }
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)); }
# File golf_prelude.rb, line 118 def call(*args, &block) proc do |recv| recv.__send__(self, *args, &block) end 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)); }
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 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)); }
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 respond 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)); }