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.id #=> 2514190 $f2.id #=> 2514190 $f3.id #=> 2514190
Returns an array of all the symbols currently in Ruby’s symbol table.
Symbol.all_symbols.size #=> 903 Symbol.all_symbols[1,20] #=> [:floor, :ARGV, :Binding, :symlink, :chown, :EOFError, :$;, :String, :LOCK_SH, :"setuid?", :$<, :default_proc, :compact, :extend, :Tms, :getwd, :$=, :ThreadGroup, :wait2, :$>]
VALUE
rb_sym_all_symbols()
{
VALUE ary = rb_ary_new2(sym_tbl->num_entries);
st_foreach(sym_tbl, symbols_i, ary);
return ary;
}
Equality—At the Object level, == returns true only if obj and other are the same object. Typically, this method is overridden in descendent classes to provide class-specific meaning.
Unlike ==, the equal? method should never be overridden by subclasses: it is used to determine object identity (that is, a.equal?(b) iff a is the same object as b).
The eql? method returns true if obj and anObject have the same value. Used by Hash to test members for equality. For objects of class Object, eql? is synonymous with ==. Subclasses normally continue this tradition, but there are exceptions. Numeric types, for example, perform type conversion across ==, but not across eql?, so:
1 == 1.0 #=> true 1.eql? 1.0 #=> false
static VALUE
rb_obj_equal(obj1, obj2)
VALUE obj1, obj2;
{
if (obj1 == obj2) return Qtrue;
return Qfalse;
}
Returns the name or string corresponding to sym.
:fred.id2name #=> "fred"
static VALUE
sym_to_s(sym)
VALUE sym;
{
return rb_str_new2(rb_id2name(SYM2ID(sym)));
}
Returns the representation of sym as a symbol literal.
:fred.inspect #=> ":fred"
static VALUE
sym_inspect(sym)
VALUE sym;
{
VALUE str;
const char *name;
ID id = SYM2ID(sym);
name = rb_id2name(id);
str = rb_str_new(0, strlen(name)+1);
RSTRING(str)->ptr[0] = ':';
strcpy(RSTRING(str)->ptr+1, name);
if (!rb_symname_p(name)) {
str = rb_str_dump(str);
strncpy(RSTRING(str)->ptr, ":\"", 2);
}
return str;
}
Returns an integer that is unique for each symbol within a particular execution of a program.
:fred.to_i #=> 9809 "fred".to_sym.to_i #=> 9809
static VALUE
sym_to_i(sym)
VALUE sym;
{
ID id = SYM2ID(sym);
return LONG2FIX(id);
}
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));
}
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