Boolean negate.
VALUE rb_obj_not(VALUE obj) { return RTEST(obj) ? Qfalse : Qtrue; }
Returns true if two objects are not-equal, otherwise false.
VALUE rb_obj_not_equal(VALUE obj1, VALUE obj2) { VALUE result = rb_funcall(obj1, id_eq, 1, obj2); return RTEST(result) ? Qfalse : Qtrue; }
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
VALUE rb_obj_equal(VALUE obj1, VALUE obj2) { if (obj1 == obj2) return Qtrue; return Qfalse; }
Invokes the method identified by symbol, passing it any arguments
specified. You can use __send__
if the name send
clashes with an existing method in obj.
class Klass def hello(*args) "Hello " + args.join(' ') end end k = Klass.new k.send :hello, "gentle", "readers" #=> "Hello gentle readers"
VALUE rb_f_send(int argc, VALUE *argv, VALUE recv) { return send_internal(argc, argv, recv, NOEX_NOSUPER | NOEX_PRIVATE); }
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
VALUE rb_obj_equal(VALUE obj1, VALUE obj2) { if (obj1 == obj2) return Qtrue; return Qfalse; }
Evaluates a string containing Ruby source code, or the given block, within
the context of the receiver (obj). In order to set the context,
the variable self
is set to obj while the code is
executing, giving the code access to obj's instance variables.
In the version of instance_eval
that takes a
String
, the optional second and third parameters supply a
filename and starting line number that are used when reporting compilation
errors.
class KlassWithSecret def initialize @secret = 99 end end k = KlassWithSecret.new k.instance_eval { @secret } #=> 99
VALUE rb_obj_instance_eval(int argc, VALUE *argv, VALUE self) { VALUE klass; if (SPECIAL_CONST_P(self)) { klass = Qnil; } else { klass = rb_singleton_class(self); } return specific_eval(argc, argv, klass, self); }
Executes the given block within the context of the receiver (obj).
In order to set the context, the variable self
is set to
obj while the code is executing, giving the code access to
obj's instance variables. Arguments are passed as block
parameters.
class KlassWithSecret def initialize @secret = 99 end end k = KlassWithSecret.new k.instance_exec(5) {|x| @secret+x } #=> 104
VALUE rb_obj_instance_exec(int argc, VALUE *argv, VALUE self) { VALUE klass; if (SPECIAL_CONST_P(self)) { klass = Qnil; } else { klass = rb_singleton_class(self); } return yield_under(klass, self, rb_ary_new4(argc, argv)); }
Invoked by Ruby when obj is sent a message it cannot handle.
symbol is the symbol for the method called, and args are
any arguments that were passed to it. By default, the interpreter raises an
error when this method is called. However, it is possible to override the
method to provide more dynamic behavior. If it is decided that a particular
method should not be handled, then super should be called, so that
ancestors can pick up the missing method. The example below creates a class
Roman
, which responds to methods with names consisting of
roman numerals, returning the corresponding integer values.
class Roman def romanToInt(str) # ... end def method_missing(methId) str = methId.id2name romanToInt(str) end end r = Roman.new r.iv #=> 4 r.xxiii #=> 23 r.mm #=> 2000
static VALUE rb_method_missing(int argc, const VALUE *argv, VALUE obj) { rb_thread_t *th = GET_THREAD(); raise_method_missing(th, argc, argv, obj, th->method_missing_reason); return Qnil; /* not reached */ }
Invoked as a callback whenever a singleton method is added to the receiver.
module Chatty def Chatty.singleton_method_added(id) puts "Adding #{id.id2name}" end def self.one() end def two() end def Chatty.three() end end
produces:
Adding singleton_method_added Adding one Adding three
static VALUE rb_obj_dummy(void) { return Qnil; }
Invoked as a callback whenever a singleton method is removed from the receiver.
module Chatty def Chatty.singleton_method_removed(id) puts "Removing #{id.id2name}" end def self.one() end def two() end def Chatty.three() end class <<self remove_method :three remove_method :one end end
produces:
Removing three Removing one
static VALUE rb_obj_dummy(void) { return Qnil; }
Invoked as a callback whenever a singleton method is undefined in the receiver.
module Chatty def Chatty.singleton_method_undefined(id) puts "Undefining #{id.id2name}" end def Chatty.one() end class << self undef_method(:one) end end
produces:
Undefining one
static VALUE rb_obj_dummy(void) { return Qnil; }