class Module
A Module is a collection of methods and constants. The methods in a module may be instance methods or module methods. Instance methods appear as methods in a class when the module is included, module methods do not. Conversely, module methods may be called without creating an encapsulating object, while instance methods may not. (See Module#module_function.)
In the descriptions that follow, the parameter sym refers to a symbol, which is either a quoted string or a Symbol (such as :name).
module Mod
include Math
CONST = 1
def meth
# ...
end
end
Mod.class #=> Module
Mod.constants #=> [:CONST, :PI, :E]
Mod.instance_methods #=> [:meth]
Public Class Methods
static VALUE
rb_mod_s_constants(int argc, VALUE *argv, VALUE mod)
{
const rb_cref_t *cref = rb_vm_cref();
VALUE klass;
VALUE cbase = 0;
void *data = 0;
if (argc > 0 || mod != rb_cModule) {
return rb_mod_constants(argc, argv, mod);
}
while (cref) {
klass = CREF_CLASS(cref);
if (!CREF_PUSHED_BY_EVAL(cref) &&
!NIL_P(klass)) {
data = rb_mod_const_at(CREF_CLASS(cref), data);
if (!cbase) {
cbase = klass;
}
}
cref = CREF_NEXT(cref);
}
if (cbase) {
data = rb_mod_const_of(cbase, data);
}
return rb_const_list(data);
} In the first form, returns an array of the names of all constants accessible from the point of call. This list includes the names of all modules and classes defined in the global scope.
Module.constants.first(4) # => [:ARGF, :ARGV, :ArgumentError, :Array] Module.constants.include?(:SEEK_SET) # => false class IO Module.constants.include?(:SEEK_SET) # => true end
The second form calls the instance method constants.
static VALUE
rb_mod_nesting(void)
{
VALUE ary = rb_ary_new();
const rb_cref_t *cref = rb_vm_cref();
while (cref && CREF_NEXT(cref)) {
VALUE klass = CREF_CLASS(cref);
if (!CREF_PUSHED_BY_EVAL(cref) &&
!NIL_P(klass)) {
rb_ary_push(ary, klass);
}
cref = CREF_NEXT(cref);
}
return ary;
} Returns the list of Modules nested at the point of call.
module M1
module M2
$a = Module.nesting
end
end
$a #=> [M1::M2, M1]
$a[0].name #=> "M1::M2"
static VALUE
rb_mod_initialize(VALUE module)
{
if (rb_block_given_p()) {
rb_mod_module_exec(1, &module, module);
}
return Qnil;
} Creates a new anonymous module. If a block is given, it is passed the module object, and the block is evaluated in the context of this module using module_eval.
fred = Module.new do
def meth1
"hello"
end
def meth2
"bye"
end
end
a = "my string"
a.extend(fred) #=> "my string"
a.meth1 #=> "hello"
a.meth2 #=> "bye"
Assign the module to a constant (name starting uppercase) if you want to treat it like a regular module.
Public Instance Methods
static VALUE
rb_mod_lt(VALUE mod, VALUE arg)
{
if (mod == arg) return Qfalse;
return rb_class_inherited_p(mod, arg);
} Returns true if mod is a subclass of other. Returns nil if there's no relationship between the two. (Think of the relationship in terms of the class definition: “class A<B” implies “A<B”.)
VALUE
rb_class_inherited_p(VALUE mod, VALUE arg)
{
VALUE start = mod;
if (mod == arg) return Qtrue;
if (!CLASS_OR_MODULE_P(arg) && !RB_TYPE_P(arg, T_ICLASS)) {
rb_raise(rb_eTypeError, "compared with non class/module");
}
arg = RCLASS_ORIGIN(arg);
if (class_search_ancestor(mod, arg)) {
return Qtrue;
}
/* not mod < arg; check if mod > arg */
if (class_search_ancestor(arg, start)) {
return Qfalse;
}
return Qnil;
} Returns true if mod is a subclass of other or is the same as other. Returns nil if there's no relationship between the two. (Think of the relationship in terms of the class definition: “class A<B” implies “A<B”.)
static VALUE
rb_mod_cmp(VALUE mod, VALUE arg)
{
VALUE cmp;
if (mod == arg) return INT2FIX(0);
if (!CLASS_OR_MODULE_P(arg)) {
return Qnil;
}
cmp = rb_class_inherited_p(mod, arg);
if (NIL_P(cmp)) return Qnil;
if (cmp) {
return INT2FIX(-1);
}
return INT2FIX(1);
} Comparison—Returns -1, 0, +1 or nil depending on whether module includes other_module, they are the same, or if module is included by other_module.
Returns nil if module has no relationship with other_module, if other_module is not a module, or if the two values are incomparable.
VALUE
rb_obj_equal(VALUE obj1, VALUE obj2)
{
if (obj1 == obj2) return Qtrue;
return Qfalse;
} Equality — At the Object level, == returns true only if obj and other are the same object. Typically, this method is overridden in descendant classes to provide class-specific meaning.
Unlike ==, the equal? method should never be overridden by subclasses as it is used to determine object identity (that is, a.equal?(b) if and only if a is the same object as b):
obj = "a" other = obj.dup obj == other #=> true obj.equal? other #=> false obj.equal? obj #=> true
The eql? method returns true if obj and other refer to the same hash key. This is used by Hash to test members for equality. For objects of class Object, eql? is synonymous with ==. Subclasses normally continue this tradition by aliasing eql? to their overridden == method, 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_mod_eqq(VALUE mod, VALUE arg)
{
return rb_obj_is_kind_of(arg, mod);
} Case Equality—Returns true if obj is an instance of mod or and instance of one of mod's descendants. Of limited use for modules, but can be used in case statements to classify objects by class.
static VALUE
rb_mod_gt(VALUE mod, VALUE arg)
{
if (mod == arg) return Qfalse;
return rb_mod_ge(mod, arg);
} Returns true if mod is an ancestor of other. Returns nil if there's no relationship between the two. (Think of the relationship in terms of the class definition: “class A<B” implies “B>A”.)
static VALUE
rb_mod_ge(VALUE mod, VALUE arg)
{
if (!CLASS_OR_MODULE_P(arg)) {
rb_raise(rb_eTypeError, "compared with non class/module");
}
return rb_class_inherited_p(arg, mod);
} Returns true if mod is an ancestor of other, or the two modules are the same. Returns nil if there's no relationship between the two. (Think of the relationship in terms of the class definition: “class A<B” implies “B>A”.)
VALUE
rb_mod_ancestors(VALUE mod)
{
VALUE p, ary = rb_ary_new();
for (p = mod; p; p = RCLASS_SUPER(p)) {
if (BUILTIN_TYPE(p) == T_ICLASS) {
rb_ary_push(ary, RBASIC(p)->klass);
}
else if (p == RCLASS_ORIGIN(p)) {
rb_ary_push(ary, p);
}
}
return ary;
} Returns a list of modules included/prepended in mod (including mod itself).
module Mod include Math include Comparable prepend Enumerable end Mod.ancestors #=> [Enumerable, Mod, Comparable, Math] Math.ancestors #=> [Math] Enumerable.ancestors #=> [Enumerable]
static VALUE
rb_mod_autoload(VALUE mod, VALUE sym, VALUE file)
{
ID id = rb_to_id(sym);
FilePathValue(file);
rb_autoload_str(mod, id, file);
return Qnil;
} Registers filename to be loaded (using Kernel::require) the first time that module (which may be a String or a symbol) is accessed in the namespace of mod.
module A end A.autoload(:B, "b") A::B.doit # autoloads "b"
static VALUE
rb_mod_autoload_p(VALUE mod, VALUE sym)
{
ID id = rb_check_id(&sym);
if (!id) {
return Qnil;
}
return rb_autoload_p(mod, id);
} Returns filename to be loaded if name is registered as autoload in the namespace of mod.
module A end A.autoload(:B, "b") A.autoload?(:B) #=> "b"
VALUE
rb_mod_module_eval(int argc, const VALUE *argv, VALUE mod)
{
return specific_eval(argc, argv, mod, mod);
} Evaluates the string or block in the context of mod, except that when a block is given, constant/class variable lookup is not affected. This can be used to add methods to a class. module_eval returns the result of evaluating its argument. The optional filename and lineno parameters set the text for error messages.
class Thing
end
a = %q{def hello() "Hello there!" end}
Thing.module_eval(a)
puts Thing.new.hello()
Thing.module_eval("invalid code", "dummy", 123)
produces:
Hello there!
dummy:123:in `module_eval': undefined local variable
or method `code' for Thing:Class VALUE
rb_mod_module_exec(int argc, const VALUE *argv, VALUE mod)
{
return yield_under(mod, mod, rb_ary_new4(argc, argv));
} Evaluates the given block in the context of the class/module. The method defined in the block will belong to the receiver. Any arguments passed to the method will be passed to the block. This can be used if the block needs to access instance variables.
class Thing
end
Thing.class_exec{
def hello() "Hello there!" end
}
puts Thing.new.hello()
produces:
Hello there!
static VALUE
rb_mod_cvar_defined(VALUE obj, VALUE iv)
{
ID id = id_for_var(obj, iv, a, class);
if (!id) {
return Qfalse;
}
return rb_cvar_defined(obj, id);
} Returns true if the given class variable is defined in obj. String arguments are converted to symbols.
class Fred @@foo = 99 end Fred.class_variable_defined?(:@@foo) #=> true Fred.class_variable_defined?(:@@bar) #=> false
static VALUE
rb_mod_cvar_get(VALUE obj, VALUE iv)
{
ID id = id_for_var(obj, iv, a, class);
if (!id) {
rb_name_err_raise("uninitialized class variable %1$s in %2$s",
obj, iv);
}
return rb_cvar_get(obj, id);
} Returns the value of the given class variable (or throws a NameError exception). The @@ part of the variable name should be included for regular class variables. String arguments are converted to symbols.
class Fred @@foo = 99 end Fred.class_variable_get(:@@foo) #=> 99
static VALUE
rb_mod_cvar_set(VALUE obj, VALUE iv, VALUE val)
{
ID id = id_for_var(obj, iv, a, class);
if (!id) id = rb_intern_str(iv);
rb_cvar_set(obj, id, val);
return val;
} Sets the class variable named by symbol to the given object. If the class variable name is passed as a string, that string is converted to a symbol.
class Fred
@@foo = 99
def foo
@@foo
end
end
Fred.class_variable_set(:@@foo, 101) #=> 101
Fred.new.foo #=> 101
VALUE
rb_mod_class_variables(int argc, const VALUE *argv, VALUE mod)
{
VALUE inherit;
st_table *tbl;
if (argc == 0) {
inherit = Qtrue;
}
else {
rb_scan_args(argc, argv, "01", &inherit);
}
if (RTEST(inherit)) {
tbl = mod_cvar_of(mod, 0);
}
else {
tbl = mod_cvar_at(mod, 0);
}
return cvar_list(tbl);
} Returns an array of the names of class variables in mod. This includes the names of class variables in any included modules, unless the inherit parameter is set to false.
class One @@var1 = 1 end class Two < One @@var2 = 2 end One.class_variables #=> [:@@var1] Two.class_variables #=> [:@@var2, :@@var1] Two.class_variables(false) #=> [:@@var2]
static VALUE
rb_mod_const_defined(int argc, VALUE *argv, VALUE mod)
{
VALUE name, recur;
rb_encoding *enc;
const char *pbeg, *p, *path, *pend;
ID id;
rb_check_arity(argc, 1, 2);
name = argv[0];
recur = (argc == 1) ? Qtrue : argv[1];
if (SYMBOL_P(name)) {
if (!rb_is_const_sym(name)) goto wrong_name;
id = rb_check_id(&name);
if (!id) return Qfalse;
return RTEST(recur) ? rb_const_defined(mod, id) : rb_const_defined_at(mod, id);
}
path = StringValuePtr(name);
enc = rb_enc_get(name);
if (!rb_enc_asciicompat(enc)) {
rb_raise(rb_eArgError, "invalid class path encoding (non ASCII)");
}
pbeg = p = path;
pend = path + RSTRING_LEN(name);
if (p >= pend || !*p) {
wrong_name:
rb_name_err_raise(wrong_constant_name, mod, name);
}
if (p + 2 < pend && p[0] == ':' && p[1] == ':') {
mod = rb_cObject;
p += 2;
pbeg = p;
}
while (p < pend) {
VALUE part;
long len, beglen;
while (p < pend && *p != ':') p++;
if (pbeg == p) goto wrong_name;
id = rb_check_id_cstr(pbeg, len = p-pbeg, enc);
beglen = pbeg-path;
if (p < pend && p[0] == ':') {
if (p + 2 >= pend || p[1] != ':') goto wrong_name;
p += 2;
pbeg = p;
}
if (!id) {
part = rb_str_subseq(name, beglen, len);
OBJ_FREEZE(part);
if (!ISUPPER(*pbeg) || !rb_is_const_name(part)) {
name = part;
goto wrong_name;
}
else {
return Qfalse;
}
}
if (!rb_is_const_id(id)) {
name = ID2SYM(id);
goto wrong_name;
}
if (RTEST(recur)) {
if (!rb_const_defined(mod, id))
return Qfalse;
mod = rb_const_get(mod, id);
}
else {
if (!rb_const_defined_at(mod, id))
return Qfalse;
mod = rb_const_get_at(mod, id);
}
recur = Qfalse;
if (p < pend && !RB_TYPE_P(mod, T_MODULE) && !RB_TYPE_P(mod, T_CLASS)) {
rb_raise(rb_eTypeError, "%"PRIsVALUE" does not refer to class/module",
QUOTE(name));
}
}
return Qtrue;
} Says whether mod or its ancestors have a constant with the given name:
Float.const_defined?(:EPSILON) #=> true, found in Float itself
Float.const_defined?("String") #=> true, found in Object (ancestor)
BasicObject.const_defined?(:Hash) #=> false
If mod is a Module, additionally Object and its ancestors are checked:
Math.const_defined?(:String) #=> true, found in Object
In each of the checked classes or modules, if the constant is not present but there is an autoload for it, true is returned directly without autoloading:
module Admin autoload :User, 'admin/user' end Admin.const_defined?(:User) #=> true
If the constant is not found the callback const_missing is not called and the method returns false.
If inherit is false, the lookup only checks the constants in the receiver:
IO.const_defined?(:SYNC) #=> true, found in File::Constants (ancestor) IO.const_defined?(:SYNC, false) #=> false, not found in IO itself
In this case, the same logic for autoloading applies.
If the argument is not a valid constant name a NameError is raised with the message “wrong constant name name”:
Hash.const_defined? 'foobar' #=> NameError: wrong constant name foobar
static VALUE
rb_mod_const_get(int argc, VALUE *argv, VALUE mod)
{
VALUE name, recur;
rb_encoding *enc;
const char *pbeg, *p, *path, *pend;
ID id;
rb_check_arity(argc, 1, 2);
name = argv[0];
recur = (argc == 1) ? Qtrue : argv[1];
if (SYMBOL_P(name)) {
if (!rb_is_const_sym(name)) goto wrong_name;
id = rb_check_id(&name);
if (!id) return rb_const_missing(mod, name);
return RTEST(recur) ? rb_const_get(mod, id) : rb_const_get_at(mod, id);
}
path = StringValuePtr(name);
enc = rb_enc_get(name);
if (!rb_enc_asciicompat(enc)) {
rb_raise(rb_eArgError, "invalid class path encoding (non ASCII)");
}
pbeg = p = path;
pend = path + RSTRING_LEN(name);
if (p >= pend || !*p) {
wrong_name:
rb_name_err_raise(wrong_constant_name, mod, name);
}
if (p + 2 < pend && p[0] == ':' && p[1] == ':') {
mod = rb_cObject;
p += 2;
pbeg = p;
}
while (p < pend) {
VALUE part;
long len, beglen;
while (p < pend && *p != ':') p++;
if (pbeg == p) goto wrong_name;
id = rb_check_id_cstr(pbeg, len = p-pbeg, enc);
beglen = pbeg-path;
if (p < pend && p[0] == ':') {
if (p + 2 >= pend || p[1] != ':') goto wrong_name;
p += 2;
pbeg = p;
}
if (!RB_TYPE_P(mod, T_MODULE) && !RB_TYPE_P(mod, T_CLASS)) {
rb_raise(rb_eTypeError, "%"PRIsVALUE" does not refer to class/module",
QUOTE(name));
}
if (!id) {
part = rb_str_subseq(name, beglen, len);
OBJ_FREEZE(part);
if (!ISUPPER(*pbeg) || !rb_is_const_name(part)) {
name = part;
goto wrong_name;
}
else if (!rb_method_basic_definition_p(CLASS_OF(mod), id_const_missing)) {
part = rb_str_intern(part);
mod = rb_const_missing(mod, part);
continue;
}
else {
rb_mod_const_missing(mod, part);
}
}
if (!rb_is_const_id(id)) {
name = ID2SYM(id);
goto wrong_name;
}
mod = RTEST(recur) ? rb_const_get(mod, id) : rb_const_get_at(mod, id);
}
return mod;
} Checks for a constant with the given name in mod. If inherit is set, the lookup will also search the ancestors (and Object if mod is a Module).
The value of the constant is returned if a definition is found, otherwise a NameError is raised.
Math.const_get(:PI) #=> 3.14159265358979
This method will recursively look up constant names if a namespaced class name is provided. For example:
module Foo; class Bar; end end Object.const_get 'Foo::Bar'
The inherit flag is respected on each lookup. For example:
module Foo
class Bar
VAL = 10
end
class Baz < Bar; end
end
Object.const_get 'Foo::Baz::VAL' # => 10
Object.const_get 'Foo::Baz::VAL', false # => NameError
If the argument is not a valid constant name a NameError will be raised with a warning “wrong constant name”.
Object.const_get 'foobar' #=> NameError: wrong constant name foobar
VALUE
rb_mod_const_missing(VALUE klass, VALUE name)
{
rb_vm_pop_cfunc_frame();
uninitialized_constant(klass, name);
UNREACHABLE;
} Invoked when a reference is made to an undefined constant in mod. It is passed a symbol for the undefined constant, and returns a value to be used for that constant. The following code is an example of the same:
def Foo.const_missing(name) name # return the constant name as Symbol end Foo::UNDEFINED_CONST #=> :UNDEFINED_CONST: symbol returned
In the next example when a reference is made to an undefined constant, it attempts to load a file whose name is the lowercase version of the constant (thus class Fred is assumed to be in file fred.rb). If found, it returns the loaded class. It therefore implements an autoload feature similar to Kernel#autoload and #autoload.
def Object.const_missing(name)
@looked_for ||= {}
str_name = name.to_s
raise "Class not found: #{name}" if @looked_for[str_name]
@looked_for[str_name] = 1
file = str_name.downcase
require file
klass = const_get(name)
return klass if klass
raise "Class not found: #{name}"
end
static VALUE
rb_mod_const_set(VALUE mod, VALUE name, VALUE value)
{
ID id = id_for_setter(mod, name, const, wrong_constant_name);
if (!id) id = rb_intern_str(name);
rb_const_set(mod, id, value);
return value;
} Sets the named constant to the given object, returning that object. Creates a new constant if no constant with the given name previously existed.
Math.const_set("HIGH_SCHOOL_PI", 22.0/7.0) #=> 3.14285714285714
Math::HIGH_SCHOOL_PI - Math::PI #=> 0.00126448926734968
If sym or str is not a valid constant name a NameError will be raised with a warning “wrong constant name”.
Object.const_set('foobar', 42) #=> NameError: wrong constant name foobar
VALUE
rb_mod_constants(int argc, const VALUE *argv, VALUE mod)
{
VALUE inherit;
if (argc == 0) {
inherit = Qtrue;
}
else {
rb_scan_args(argc, argv, "01", &inherit);
}
if (RTEST(inherit)) {
return rb_const_list(rb_mod_const_of(mod, 0));
}
else {
return rb_local_constants(mod);
}
} Returns an array of the names of the constants accessible in mod. This includes the names of constants in any included modules (example at start of section), unless the inherit parameter is set to false.
The implementation makes no guarantees about the order in which the constants are yielded.
IO.constants.include?(:SYNC) #=> true IO.constants(false).include?(:SYNC) #=> false
Also see Module::const_defined?.
VALUE
rb_mod_deprecate_constant(int argc, const VALUE *argv, VALUE obj)
{
set_const_visibility(obj, argc, argv, CONST_DEPRECATED, CONST_DEPRECATED);
return obj;
} static VALUE
rb_mod_freeze(VALUE mod)
{
rb_class_name(mod);
return rb_obj_freeze(mod);
} Prevents further modifications to mod.
This method returns self.
static VALUE
rb_mod_include(int argc, VALUE *argv, VALUE module)
{
int i;
ID id_append_features, id_included;
CONST_ID(id_append_features, "append_features");
CONST_ID(id_included, "included");
for (i = 0; i < argc; i++)
Check_Type(argv[i], T_MODULE);
while (argc--) {
rb_funcall(argv[argc], id_append_features, 1, module);
rb_funcall(argv[argc], id_included, 1, module);
}
return module;
} Invokes Module.append_features on each parameter in reverse order.
VALUE
rb_mod_include_p(VALUE mod, VALUE mod2)
{
VALUE p;
Check_Type(mod2, T_MODULE);
for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
if (BUILTIN_TYPE(p) == T_ICLASS) {
if (RBASIC(p)->klass == mod2) return Qtrue;
}
}
return Qfalse;
} Returns true if module is included in mod or one of mod's ancestors.
module A end class B include A end class C < B end B.include?(A) #=> true C.include?(A) #=> true A.include?(A) #=> false
VALUE
rb_mod_included_modules(VALUE mod)
{
VALUE ary = rb_ary_new();
VALUE p;
VALUE origin = RCLASS_ORIGIN(mod);
for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
if (p != origin && BUILTIN_TYPE(p) == T_ICLASS) {
VALUE m = RBASIC(p)->klass;
if (RB_TYPE_P(m, T_MODULE))
rb_ary_push(ary, m);
}
}
return ary;
} Returns the list of modules included in mod.
module Mixin end module Outer include Mixin end Mixin.included_modules #=> [] Outer.included_modules #=> [Mixin]
static VALUE
rb_mod_instance_method(VALUE mod, VALUE vid)
{
ID id = rb_check_id(&vid);
if (!id) {
rb_method_name_error(mod, vid);
}
return mnew(mod, Qundef, id, rb_cUnboundMethod, FALSE);
} Returns an UnboundMethod representing the given instance method in mod.
class Interpreter
def do_a() print "there, "; end
def do_d() print "Hello "; end
def do_e() print "!\n"; end
def do_v() print "Dave"; end
Dispatcher = {
"a" => instance_method(:do_a),
"d" => instance_method(:do_d),
"e" => instance_method(:do_e),
"v" => instance_method(:do_v)
}
def interpret(string)
string.each_char {|b| Dispatcher[b].bind(self).call }
end
end
interpreter = Interpreter.new
interpreter.interpret('dave')
produces:
Hello there, Dave!
VALUE
rb_class_instance_methods(int argc, const VALUE *argv, VALUE mod)
{
return class_instance_method_list(argc, argv, mod, 0, ins_methods_i);
} Returns an array containing the names of the public and protected instance methods in the receiver. For a module, these are the public and protected methods; for a class, they are the instance (not singleton) methods. If the optional parameter is false, the methods of any ancestors are not included.
module A def method1() end end class B include A def method2() end end class C < B def method3() end end A.instance_methods(false) #=> [:method1] B.instance_methods(false) #=> [:method2] B.instance_methods(true).include?(:method1) #=> true C.instance_methods(false) #=> [:method3] C.instance_methods.include?(:method2) #=> true
static VALUE
rb_mod_method_defined(VALUE mod, VALUE mid)
{
ID id = rb_check_id(&mid);
if (!id || !rb_method_boundp(mod, id, 1)) {
return Qfalse;
}
return Qtrue;
} Returns true if the named method is defined by mod (or its included modules and, if mod is a class, its ancestors). Public and protected methods are matched. String arguments are converted to symbols.
module A def method1() end def protected_method1() end protected :protected_method1 end class B def method2() end def private_method2() end private :private_method2 end class C < B include A def method3() end end A.method_defined? :method1 #=> true C.method_defined? "method1" #=> true C.method_defined? "method2" #=> true C.method_defined? "method3" #=> true C.method_defined? "protected_method1" #=> true C.method_defined? "method4" #=> false C.method_defined? "private_method2" #=> false
VALUE
rb_mod_module_eval(int argc, const VALUE *argv, VALUE mod)
{
return specific_eval(argc, argv, mod, mod);
} Evaluates the string or block in the context of mod, except that when a block is given, constant/class variable lookup is not affected. This can be used to add methods to a class. module_eval returns the result of evaluating its argument. The optional filename and lineno parameters set the text for error messages.
class Thing
end
a = %q{def hello() "Hello there!" end}
Thing.module_eval(a)
puts Thing.new.hello()
Thing.module_eval("invalid code", "dummy", 123)
produces:
Hello there!
dummy:123:in `module_eval': undefined local variable
or method `code' for Thing:Class VALUE
rb_mod_module_exec(int argc, const VALUE *argv, VALUE mod)
{
return yield_under(mod, mod, rb_ary_new4(argc, argv));
} Evaluates the given block in the context of the class/module. The method defined in the block will belong to the receiver. Any arguments passed to the method will be passed to the block. This can be used if the block needs to access instance variables.
class Thing
end
Thing.class_exec{
def hello() "Hello there!" end
}
puts Thing.new.hello()
produces:
Hello there!
VALUE
rb_mod_name(VALUE mod)
{
int permanent;
VALUE path = classname(mod, &permanent);
if (!NIL_P(path)) return rb_str_dup(path);
return path;
} Returns the name of the module mod. Returns nil for anonymous modules.
static VALUE
rb_mod_prepend(int argc, VALUE *argv, VALUE module)
{
int i;
ID id_prepend_features, id_prepended;
CONST_ID(id_prepend_features, "prepend_features");
CONST_ID(id_prepended, "prepended");
for (i = 0; i < argc; i++)
Check_Type(argv[i], T_MODULE);
while (argc--) {
rb_funcall(argv[argc], id_prepend_features, 1, module);
rb_funcall(argv[argc], id_prepended, 1, module);
}
return module;
} Invokes Module.prepend_features on each parameter in reverse order.
static VALUE
rb_mod_private_method(int argc, VALUE *argv, VALUE obj)
{
set_method_visibility(rb_singleton_class(obj), argc, argv, METHOD_VISI_PRIVATE);
return obj;
} Makes existing class methods private. Often used to hide the default constructor new.
String arguments are converted to symbols.
class SimpleSingleton # Not thread safe
private_class_method :new
def SimpleSingleton.create(*args, &block)
@me = new(*args, &block) if ! @me
@me
end
end
VALUE
rb_mod_private_constant(int argc, const VALUE *argv, VALUE obj)
{
set_const_visibility(obj, argc, argv, CONST_PRIVATE, CONST_VISIBILITY_MASK);
return obj;
} Makes a list of existing constants private.
VALUE
rb_class_private_instance_methods(int argc, const VALUE *argv, VALUE mod)
{
return class_instance_method_list(argc, argv, mod, 0, ins_methods_priv_i);
} Returns a list of the private instance methods defined in mod. If the optional parameter is false, the methods of any ancestors are not included.
module Mod def method1() end private :method1 def method2() end end Mod.instance_methods #=> [:method2] Mod.private_instance_methods #=> [:method1]
static VALUE
rb_mod_private_method_defined(VALUE mod, VALUE mid)
{
return check_definition(mod, mid, METHOD_VISI_PRIVATE);
} Returns true if the named private method is defined by _ mod_ (or its included modules and, if mod is a class, its ancestors). String arguments are converted to symbols.
module A def method1() end end class B private def method2() end end class C < B include A def method3() end end A.method_defined? :method1 #=> true C.private_method_defined? "method1" #=> false C.private_method_defined? "method2" #=> true C.method_defined? "method2" #=> false
VALUE
rb_class_protected_instance_methods(int argc, const VALUE *argv, VALUE mod)
{
return class_instance_method_list(argc, argv, mod, 0, ins_methods_prot_i);
} Returns a list of the protected instance methods defined in mod. If the optional parameter is false, the methods of any ancestors are not included.
static VALUE
rb_mod_protected_method_defined(VALUE mod, VALUE mid)
{
return check_definition(mod, mid, METHOD_VISI_PROTECTED);
} Returns true if the named protected method is defined by mod (or its included modules and, if mod is a class, its ancestors). String arguments are converted to symbols.
module A def method1() end end class B protected def method2() end end class C < B include A def method3() end end A.method_defined? :method1 #=> true C.protected_method_defined? "method1" #=> false C.protected_method_defined? "method2" #=> true C.method_defined? "method2" #=> true
# File ext/psych/lib/psych/core_ext.rb, line 22
def psych_yaml_as url
return if caller[0].end_with?('rubytypes.rb')
if $VERBOSE
warn "#{caller[0]}: yaml_as is deprecated, please use yaml_tag"
end
Psych.add_tag(url, self)
end static VALUE
rb_mod_public_method(int argc, VALUE *argv, VALUE obj)
{
set_method_visibility(rb_singleton_class(obj), argc, argv, METHOD_VISI_PUBLIC);
return obj;
} Makes a list of existing class methods public.
String arguments are converted to symbols.
VALUE
rb_mod_public_constant(int argc, const VALUE *argv, VALUE obj)
{
set_const_visibility(obj, argc, argv, CONST_PUBLIC, CONST_VISIBILITY_MASK);
return obj;
} Makes a list of existing constants public.
static VALUE
rb_mod_public_instance_method(VALUE mod, VALUE vid)
{
ID id = rb_check_id(&vid);
if (!id) {
rb_method_name_error(mod, vid);
}
return mnew(mod, Qundef, id, rb_cUnboundMethod, TRUE);
} Similar to instance_method, searches public method only.
VALUE
rb_class_public_instance_methods(int argc, const VALUE *argv, VALUE mod)
{
return class_instance_method_list(argc, argv, mod, 0, ins_methods_pub_i);
} Returns a list of the public instance methods defined in mod. If the optional parameter is false, the methods of any ancestors are not included.
static VALUE
rb_mod_public_method_defined(VALUE mod, VALUE mid)
{
return check_definition(mod, mid, METHOD_VISI_PUBLIC);
} Returns true if the named public method is defined by mod (or its included modules and, if mod is a class, its ancestors). String arguments are converted to symbols.
module A def method1() end end class B protected def method2() end end class C < B include A def method3() end end A.method_defined? :method1 #=> true C.public_method_defined? "method1" #=> true C.public_method_defined? "method2" #=> false C.method_defined? "method2" #=> true
VALUE
rb_mod_remove_cvar(VALUE mod, VALUE name)
{
const ID id = id_for_var_message(mod, name, class, "wrong class variable name %1$s");
st_data_t val, n = id;
if (!id) {
not_defined:
rb_name_err_raise("class variable %1$s not defined for %2$s",
mod, name);
}
rb_check_frozen(mod);
if (RCLASS_IV_TBL(mod) && st_delete(RCLASS_IV_TBL(mod), &n, &val)) {
return (VALUE)val;
}
if (rb_cvar_defined(mod, id)) {
rb_name_err_raise("cannot remove %1$s for %2$s", mod, ID2SYM(id));
}
goto not_defined;
} Removes the definition of the sym, returning that constant's value.
class Dummy @@var = 99 puts @@var remove_class_variable(:@@var) p(defined? @@var) end
produces:
99 nil
static VALUE
rb_mod_singleton_p(VALUE klass)
{
if (RB_TYPE_P(klass, T_CLASS) && FL_TEST(klass, FL_SINGLETON))
return Qtrue;
return Qfalse;
} Returns true if mod is a singleton class or false if it is an ordinary class or module.
class C end C.singleton_class? #=> false C.singleton_class.singleton_class? #=> true
static VALUE
rb_mod_to_s(VALUE klass)
{
ID id_defined_at;
VALUE refined_class, defined_at;
if (FL_TEST(klass, FL_SINGLETON)) {
VALUE s = rb_usascii_str_new2("#<Class:");
VALUE v = rb_ivar_get(klass, id__attached__);
if (CLASS_OR_MODULE_P(v)) {
rb_str_append(s, rb_inspect(v));
}
else {
rb_str_append(s, rb_any_to_s(v));
}
rb_str_cat2(s, ">");
return s;
}
refined_class = rb_refinement_module_get_refined_class(klass);
if (!NIL_P(refined_class)) {
VALUE s = rb_usascii_str_new2("#<refinement:");
rb_str_concat(s, rb_inspect(refined_class));
rb_str_cat2(s, "@");
CONST_ID(id_defined_at, "__defined_at__");
defined_at = rb_attr_get(klass, id_defined_at);
rb_str_concat(s, rb_inspect(defined_at));
rb_str_cat2(s, ">");
return s;
}
return rb_str_dup(rb_class_name(klass));
} Returns a string representing this module or class. For basic classes and modules, this is the name. For singletons, we show information on the thing we're attached to as well.
Private Instance Methods
static VALUE
rb_mod_alias_method(VALUE mod, VALUE newname, VALUE oldname)
{
ID oldid = rb_check_id(&oldname);
if (!oldid) {
rb_print_undef_str(mod, oldname);
}
rb_alias(mod, rb_to_id(newname), oldid);
return mod;
} Makes new_name a new copy of the method old_name. This can be used to retain access to methods that are overridden.
module Mod
alias_method :orig_exit, :exit
def exit(code=0)
puts "Exiting with code #{code}"
orig_exit(code)
end
end
include Mod
exit(99)
produces:
Exiting with code 99
static VALUE
rb_mod_append_features(VALUE module, VALUE include)
{
if (!CLASS_OR_MODULE_P(include)) {
Check_Type(include, T_CLASS);
}
rb_include_module(include, module);
return module;
} When this module is included in another, Ruby calls append_features in this module, passing it the receiving module in mod. Ruby's default implementation is to add the constants, methods, and module variables of this module to mod if this module has not already been added to mod or one of its ancestors. See also Module#include.
VALUE
rb_mod_attr(int argc, VALUE *argv, VALUE klass)
{
if (argc == 2 && (argv[1] == Qtrue || argv[1] == Qfalse)) {
rb_warning("optional boolean argument is obsoleted");
rb_attr(klass, id_for_attr(klass, argv[0]), 1, RTEST(argv[1]), TRUE);
return Qnil;
}
return rb_mod_attr_reader(argc, argv, klass);
} static VALUE
rb_mod_attr_accessor(int argc, VALUE *argv, VALUE klass)
{
int i;
for (i=0; i<argc; i++) {
rb_attr(klass, id_for_attr(klass, argv[i]), TRUE, TRUE, TRUE);
}
return Qnil;
} Defines a named attribute for this module, where the name is symbol.id2name, creating an instance variable (@name) and a corresponding access method to read it. Also creates a method called name= to set the attribute. String arguments are converted to symbols.
module Mod attr_accessor(:one, :two) end Mod.instance_methods.sort #=> [:one, :one=, :two, :two=]
static VALUE
rb_mod_attr_reader(int argc, VALUE *argv, VALUE klass)
{
int i;
for (i=0; i<argc; i++) {
rb_attr(klass, id_for_attr(klass, argv[i]), TRUE, FALSE, TRUE);
}
return Qnil;
} Creates instance variables and corresponding methods that return the value of each instance variable. Equivalent to calling “attr:name'' on each name in turn. String arguments are converted to symbols.
static VALUE
rb_mod_attr_writer(int argc, VALUE *argv, VALUE klass)
{
int i;
for (i=0; i<argc; i++) {
rb_attr(klass, id_for_attr(klass, argv[i]), FALSE, TRUE, TRUE);
}
return Qnil;
} Creates an accessor method to allow assignment to the attribute symbol.id2name. String arguments are converted to symbols.
static VALUE
rb_mod_define_method(int argc, VALUE *argv, VALUE mod)
{
ID id;
VALUE body;
VALUE name;
const rb_cref_t *cref = rb_vm_cref_in_context(mod, mod);
const rb_scope_visibility_t default_scope_visi = {METHOD_VISI_PUBLIC, FALSE};
const rb_scope_visibility_t *scope_visi = &default_scope_visi;
int is_method = FALSE;
if (cref) {
scope_visi = CREF_SCOPE_VISI(cref);
}
rb_check_arity(argc, 1, 2);
name = argv[0];
id = rb_check_id(&name);
if (argc == 1) {
#if PROC_NEW_REQUIRES_BLOCK
body = rb_block_lambda();
#else
rb_thread_t *th = GET_THREAD();
rb_block_t *block = rb_vm_control_frame_block_ptr(th->cfp);
if (!block) rb_raise(rb_eArgError, proc_without_block);
body = block->proc;
if (SYMBOL_P(body)) {
body = rb_sym_to_proc(body);
}
else if (!body) {
body = rb_vm_make_proc_lambda(th, block, rb_cProc, TRUE);
}
#endif
}
else {
body = argv[1];
if (rb_obj_is_method(body)) {
is_method = TRUE;
}
else if (rb_obj_is_proc(body)) {
is_method = FALSE;
}
else {
rb_raise(rb_eTypeError,
"wrong argument type %s (expected Proc/Method)",
rb_obj_classname(body));
}
}
if (!id) id = rb_to_id(name);
if (is_method) {
struct METHOD *method = (struct METHOD *)DATA_PTR(body);
if (method->me->owner != mod && !RB_TYPE_P(method->me->owner, T_MODULE) &&
!RTEST(rb_class_inherited_p(mod, method->me->owner))) {
if (FL_TEST(method->me->owner, FL_SINGLETON)) {
rb_raise(rb_eTypeError,
"can't bind singleton method to a different class");
}
else {
rb_raise(rb_eTypeError,
"bind argument must be a subclass of % "PRIsVALUE,
rb_class_name(method->me->owner));
}
}
rb_method_entry_set(mod, id, method->me, scope_visi->method_visi);
if (scope_visi->module_func) {
rb_method_entry_set(rb_singleton_class(mod), id, method->me, METHOD_VISI_PUBLIC);
}
RB_GC_GUARD(body);
}
else {
rb_proc_t *proc;
body = proc_dup(body);
GetProcPtr(body, proc);
if (RUBY_VM_NORMAL_ISEQ_P(proc->block.iseq)) {
proc->is_lambda = TRUE;
proc->is_from_method = TRUE;
}
rb_add_method(mod, id, VM_METHOD_TYPE_BMETHOD, (void *)body, scope_visi->method_visi);
if (scope_visi->module_func) {
rb_add_method(rb_singleton_class(mod), id, VM_METHOD_TYPE_BMETHOD, (void *)body, METHOD_VISI_PUBLIC);
}
}
return ID2SYM(id);
} Defines an instance method in the receiver. The method parameter can be a Proc, a Method or an UnboundMethod object. If a block is specified, it is used as the method body. This block is evaluated using instance_eval, a point that is tricky to demonstrate because define_method is private. (This is why we resort to the send hack in this example.)
class A
def fred
puts "In Fred"
end
def create_method(name, &block)
self.class.send(:define_method, name, &block)
end
define_method(:wilma) { puts "Charge it!" }
end
class B < A
define_method(:barney, instance_method(:fred))
end
a = B.new
a.barney
a.wilma
a.create_method(:betty) { p self }
a.betty
produces:
In Fred Charge it! #<B:0x401b39e8>
static VALUE
rb_mod_extend_object(VALUE mod, VALUE obj)
{
rb_extend_object(obj, mod);
return obj;
} Extends the specified object by adding this module's constants and methods (which are added as singleton methods). This is the callback method used by Object#extend.
module Picky
def Picky.extend_object(o)
if String === o
puts "Can't add Picky to a String"
else
puts "Picky added to #{o.class}"
super
end
end
end
(s = Array.new).extend Picky # Call Object.extend
(s = "quick brown fox").extend Picky
produces:
Picky added to Array Can't add Picky to a String
static VALUE
rb_obj_dummy(void)
{
return Qnil;
} The equivalent of included, but for extended modules.
module A
def self.extended(mod)
puts "#{self} extended in #{mod}"
end
end
module Enumerable
extend A
end
# => prints "A extended in Enumerable"
static VALUE
rb_obj_dummy(void)
{
return Qnil;
} Callback invoked whenever the receiver is included in another module or class. This should be used in preference to Module.append_features if your code wants to perform some action when a module is included in another.
module A
def A.included(mod)
puts "#{self} included in #{mod}"
end
end
module Enumerable
include A
end
# => prints "A included in Enumerable"
static VALUE
rb_obj_dummy(void)
{
return Qnil;
} Invoked as a callback whenever an instance method is added to the receiver.
module Chatty
def self.method_added(method_name)
puts "Adding #{method_name.inspect}"
end
def self.some_class_method() end
def some_instance_method() end
end
produces:
Adding :some_instance_method
static VALUE
rb_obj_dummy(void)
{
return Qnil;
} Invoked as a callback whenever an instance method is removed from the receiver.
module Chatty
def self.method_removed(method_name)
puts "Removing #{method_name.inspect}"
end
def self.some_class_method() end
def some_instance_method() end
class << self
remove_method :some_class_method
end
remove_method :some_instance_method
end
produces:
Removing :some_instance_method
static VALUE
rb_obj_dummy(void)
{
return Qnil;
} Not documented
static VALUE
rb_mod_modfunc(int argc, VALUE *argv, VALUE module)
{
int i;
ID id;
const rb_method_entry_t *me;
if (!RB_TYPE_P(module, T_MODULE)) {
rb_raise(rb_eTypeError, "module_function must be called for modules");
}
if (argc == 0) {
rb_scope_module_func_set();
return module;
}
set_method_visibility(module, argc, argv, METHOD_VISI_PRIVATE);
for (i = 0; i < argc; i++) {
VALUE m = module;
id = rb_to_id(argv[i]);
for (;;) {
me = search_method(m, id, 0);
if (me == 0) {
me = search_method(rb_cObject, id, 0);
}
if (UNDEFINED_METHOD_ENTRY_P(me)) {
rb_print_undef(module, id, 0);
}
if (me->def->type != VM_METHOD_TYPE_ZSUPER) {
break; /* normal case: need not to follow 'super' link */
}
m = RCLASS_SUPER(m);
if (!m)
break;
}
rb_method_entry_set(rb_singleton_class(module), id, me, METHOD_VISI_PUBLIC);
}
return module;
} Creates module functions for the named methods. These functions may be called with the module as a receiver, and also become available as instance methods to classes that mix in the module. Module functions are copies of the original, and so may be changed independently. The instance-method versions are made private. If used with no arguments, subsequently defined methods become module functions. String arguments are converted to symbols.
module Mod
def one
"This is one"
end
module_function :one
end
class Cls
include Mod
def call_one
one
end
end
Mod.one #=> "This is one"
c = Cls.new
c.call_one #=> "This is one"
module Mod
def one
"This is the new one"
end
end
Mod.one #=> "This is one"
c.call_one #=> "This is the new one"
static VALUE
rb_mod_prepend_features(VALUE module, VALUE prepend)
{
if (!CLASS_OR_MODULE_P(prepend)) {
Check_Type(prepend, T_CLASS);
}
rb_prepend_module(prepend, module);
return module;
} When this module is prepended in another, Ruby calls prepend_features in this module, passing it the receiving module in mod. Ruby's default implementation is to overlay the constants, methods, and module variables of this module to mod if this module has not already been added to mod or one of its ancestors. See also Module#prepend.
static VALUE
rb_obj_dummy(void)
{
return Qnil;
} The equivalent of included, but for prepended modules.
module A
def self.prepended(mod)
puts "#{self} prepended to #{mod}"
end
end
module Enumerable
prepend A
end
# => prints "A prepended to Enumerable"
static VALUE
rb_mod_private(int argc, VALUE *argv, VALUE module)
{
return set_visibility(argc, argv, module, METHOD_VISI_PRIVATE);
} With no arguments, sets the default visibility for subsequently defined methods to private. With arguments, sets the named methods to have private visibility. String arguments are converted to symbols.
module Mod def a() end def b() end private def c() end private :a end Mod.private_instance_methods #=> [:a, :c]
static VALUE
rb_mod_protected(int argc, VALUE *argv, VALUE module)
{
return set_visibility(argc, argv, module, METHOD_VISI_PROTECTED);
} With no arguments, sets the default visibility for subsequently defined methods to protected. With arguments, sets the named methods to have protected visibility. String arguments are converted to symbols.
static VALUE
rb_mod_public(int argc, VALUE *argv, VALUE module)
{
return set_visibility(argc, argv, module, METHOD_VISI_PUBLIC);
} With no arguments, sets the default visibility for subsequently defined methods to public. With arguments, sets the named methods to have public visibility. String arguments are converted to symbols.
static VALUE
rb_mod_refine(VALUE module, VALUE klass)
{
VALUE refinement;
ID id_refinements, id_activated_refinements,
id_refined_class, id_defined_at;
VALUE refinements, activated_refinements;
rb_thread_t *th = GET_THREAD();
rb_block_t *block = rb_vm_control_frame_block_ptr(th->cfp);
if (!block) {
rb_raise(rb_eArgError, "no block given");
}
if (block->proc) {
rb_raise(rb_eArgError,
"can't pass a Proc as a block to Module#refine");
}
Check_Type(klass, T_CLASS);
CONST_ID(id_refinements, "__refinements__");
refinements = rb_attr_get(module, id_refinements);
if (NIL_P(refinements)) {
refinements = hidden_identity_hash_new();
rb_ivar_set(module, id_refinements, refinements);
}
CONST_ID(id_activated_refinements, "__activated_refinements__");
activated_refinements = rb_attr_get(module, id_activated_refinements);
if (NIL_P(activated_refinements)) {
activated_refinements = hidden_identity_hash_new();
rb_ivar_set(module, id_activated_refinements,
activated_refinements);
}
refinement = rb_hash_lookup(refinements, klass);
if (NIL_P(refinement)) {
refinement = rb_module_new();
RCLASS_SET_SUPER(refinement, klass);
FL_SET(refinement, RMODULE_IS_REFINEMENT);
CONST_ID(id_refined_class, "__refined_class__");
rb_ivar_set(refinement, id_refined_class, klass);
CONST_ID(id_defined_at, "__defined_at__");
rb_ivar_set(refinement, id_defined_at, module);
rb_hash_aset(refinements, klass, refinement);
add_activated_refinement(activated_refinements, klass, refinement);
}
rb_yield_refine_block(refinement, activated_refinements);
return refinement;
} Refine klass in the receiver.
Returns an overlaid module.
VALUE
rb_mod_remove_const(VALUE mod, VALUE name)
{
const ID id = id_for_var(mod, name, a, constant);
if (!id) {
rb_name_err_raise("constant %2$s::%1$s not defined",
mod, name);
}
return rb_const_remove(mod, id);
} Removes the definition of the given constant, returning that constant's previous value. If that constant referred to a module, this will not change that module's name and can lead to confusion.
static VALUE
rb_mod_remove_method(int argc, VALUE *argv, VALUE mod)
{
int i;
for (i = 0; i < argc; i++) {
VALUE v = argv[i];
ID id = rb_check_id(&v);
if (!id) {
rb_name_err_raise("method `%1$s' not defined in %2$s",
mod, v);
}
remove_method(mod, id);
}
return mod;
} Removes the method identified by symbol from the current class. For an example, see Module.undef_method. String arguments are converted to symbols.
static VALUE
rb_mod_undef_method(int argc, VALUE *argv, VALUE mod)
{
int i;
for (i = 0; i < argc; i++) {
VALUE v = argv[i];
ID id = rb_check_id(&v);
if (!id) {
rb_method_name_error(mod, v);
}
rb_undef(mod, id);
}
return mod;
} Prevents the current class from responding to calls to the named method. Contrast this with remove_method, which deletes the method from the particular class; Ruby will still search superclasses and mixed-in modules for a possible receiver. String arguments are converted to symbols.
class Parent
def hello
puts "In parent"
end
end
class Child < Parent
def hello
puts "In child"
end
end
c = Child.new
c.hello
class Child
remove_method :hello # remove from child, still in parent
end
c.hello
class Child
undef_method :hello # prevent any calls to 'hello'
end
c.hello
produces:
In child In parent prog.rb:23: undefined method `hello' for #<Child:0x401b3bb4> (NoMethodError)
static VALUE
mod_using(VALUE self, VALUE module)
{
rb_control_frame_t *prev_cfp = previous_frame(GET_THREAD());
if (prev_frame_func()) {
rb_raise(rb_eRuntimeError,
"Module#using is not permitted in methods");
}
if (prev_cfp && prev_cfp->self != self) {
rb_raise(rb_eRuntimeError, "Module#using is not called on self");
}
rb_using_module(rb_vm_cref_replace_with_duplicated_cref(), module);
return self;
} Import class refinements from module into the current class or module definition.
Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.