static VALUErb_obj_not_match(VALUE obj1, VALUE obj2){    VALUE result = rb_funcall(obj1, id_match, 1, obj2);    return rb_obj_not(result);}

Returns true if two objects do not match (using the=~ method), otherwise false.

static VALUErb_obj_cmp(VALUE obj1, VALUE obj2){    if (rb_equal(obj1, obj2))        return INT2FIX(0);    return Qnil;}

Returns 0 ifobj andother are the same object orobj == other, otherwise nil.

The<=> is used by various methods to compare objects, for exampleEnumerable#sort,Enumerable#max etc.

Your implementation of<=> should return one of the following values: -1, 0, 1 or nil. -1 means self is smaller than other. 0 means self is equal to other. 1 means self is bigger than other. Nil means the two values could not be compared.

When you define<=>, you can includeComparable to gain the methods<=,<,==, >=, > and between?.

#define case_equal rb_equal

Returnstrue orfalse.

LikeObject#==, ifobject is an instance ofObject (and not an instance of one of its many subclasses).

This method is commonly overridden by those subclasses, to provide meaningful semantics incase statements.

# File lib/delegate.rb, line 394defDelegateClass(superclass,&block)klass =Class.new(Delegator)ignores = [*::Delegator.public_api,:to_s,:inspect,:=~,:!~,:===]protected_instance_methods =superclass.protected_instance_methodsprotected_instance_methods-=ignorespublic_instance_methods =superclass.public_instance_methodspublic_instance_methods-=ignoresklass.module_evaldodef__getobj__# :nodoc:unlessdefined?(@delegate_dc_obj)returnyieldifblock_given?__raise__::ArgumentError,"not delegated"end@delegate_dc_objenddef__setobj__(obj)# :nodoc:__raise__::ArgumentError,"cannot delegate to self"ifself.equal?(obj)@delegate_dc_obj =objendprotected_instance_methods.eachdo|method|define_method(method,Delegator.delegating_block(method))protectedmethodendpublic_instance_methods.eachdo|method|define_method(method,Delegator.delegating_block(method))endendklass.define_singleton_method:public_instance_methodsdo|all=true|super(all)|superclass.public_instance_methodsendklass.define_singleton_method:protected_instance_methodsdo|all=true|super(all)|superclass.protected_instance_methodsendklass.define_singleton_method:instance_methodsdo|all=true|super(all)|superclass.instance_methodsendklass.define_singleton_method:public_instance_methoddo|name|super(name)rescueNameErrorraiseunlessself.public_instance_methods.include?(name)superclass.public_instance_method(name)endklass.define_singleton_method:instance_methoddo|name|super(name)rescueNameErrorraiseunlessself.instance_methods.include?(name)superclass.instance_method(name)endklass.module_eval(&block)ifblockreturnklassend

The primary interface to this library. Use to setup delegation when defining your class.

classMyClass<DelegateClass(ClassToDelegateTo)# Step 1definitializesuper(obj_of_ClassToDelegateTo)# Step 2endend

or:

MyClass =DelegateClass(ClassToDelegateTo)do# Step 1definitializesuper(obj_of_ClassToDelegateTo)# Step 2endend

Here’s a sample of use fromTempfile which is really aFile object with a few special rules about storage location and when theFile should be deleted. That makes for an almost textbook perfect example of how to use delegation.

classTempfile<DelegateClass(File)# constant and class member data initialization...definitialize(basename,tmpdir=Dir::tmpdir)# build up file path/name in var tmpname...@tmpfile =File.open(tmpname,File::RDWR|File::CREAT|File::EXCL,0600)# ...super(@tmpfile)# below this point, all methods of File are supported...end# ...end

# File ext/digest/lib/digest.rb, line 110defDigest(name)const =name.to_symDigest::REQUIRE_MUTEX.synchronize {# Ignore autoload's because it is void when we have #const_missingDigest.const_missing(const)  }rescueLoadError# Constants do not necessarily rely on digest/*.ifDigest.const_defined?(const)Digest.const_get(const)elseraiseendend

Returns aDigest subclass byname in a thread-safe manner even when on-demand loading is involved.

require'digest'Digest("MD5")# => Digest::MD5Digest(:SHA256)# => Digest::SHA256Digest(:Foo)# => LoadError: library not found for class Digest::Foo -- digest/foo

static VALUErb_obj_define_method(int argc, VALUE *argv, VALUE obj){    VALUE klass = rb_singleton_class(obj);    const rb_scope_visibility_t scope_visi = {METHOD_VISI_PUBLIC, FALSE};    return rb_mod_define_method_with_visibility(argc, argv, klass, &scope_visi);}

Defines a public singleton method in the receiver. Themethod parameter can be aProc, aMethod or anUnboundMethod object. If a block is specified, it is used as the method body. If a block or a method has parameters, they’re used as method parameters.

classAclass<<selfdefclass_nameto_sendendendA.define_singleton_method(:who_am_i)do"I am: #{class_name}"endA.who_am_i# ==> "I am: A"guy ="Bob"guy.define_singleton_method(:hello) {"#{self}: Hello there!" }guy.hello#=>  "Bob: Hello there!"chris ="Chris"chris.define_singleton_method(:greet) {|greeting|"#{greeting}, I'm Chris!" }chris.greet("Hi")#=> "Hi, I'm Chris!"

static VALUErb_obj_display(int argc, VALUE *argv, VALUE self){    VALUE out;    out = (!rb_check_arity(argc, 0, 1) ? rb_ractor_stdout() : argv[0]);    rb_io_write(out, self);    return Qnil;}

Writesself on the given port:

1.display"cat".display[4,5,6 ].displayputs

Output:

1cat[4, 5, 6]

VALUErb_obj_dup(VALUE obj){    VALUE dup;    if (special_object_p(obj)) {        return obj;    }    dup = rb_obj_alloc(rb_obj_class(obj));    return rb_obj_dup_setup(obj, dup);}

Produces a shallow copy ofobj—the instance variables ofobj are copied, but not the objects they reference.

This method may have class-specific behavior. If so, that behavior will be documented under the #initialize_copy method of the class.

on dup vs clone¶↑

In general,clone anddup may have different semantics in descendant classes. Whileclone is used to duplicate an object, including its internal state,dup typically uses the class of the descendant object to create the new instance.

When usingdup, any modules that the object has been extended with will not be copied.

classKlassattr_accessor:strendmoduleFoodeffoo;'foo';endends1 =Klass.new#=> #<Klass:0x401b3a38>s1.extend(Foo)#=> #<Klass:0x401b3a38>s1.foo#=> "foo"s2 =s1.clone#=> #<Klass:0x401be280>s2.foo#=> "foo"s3 =s1.dup#=> #<Klass:0x401c1084>s3.foo#=> NoMethodError: undefined method `foo' for #<Klass:0x401c1084>

Creates a newEnumerator which will enumerate by callingmethod onobj, passingargs if any. What wasyielded by method becomes values of enumerator.

If a block is given, it will be used to calculate the size of the enumerator without the need to iterate it (seeEnumerator#size).

Examples¶↑

str ="xyz"enum =str.enum_for(:each_byte)enum.each {|b|putsb }# => 120# => 121# => 122# protect an array from being modified by some_methoda = [1,2,3]some_method(a.to_enum)# String#split in block form is more memory-effective:very_large_string.split("|") {|chunk|returnchunkifchunk.include?('DATE') }# This could be rewritten more idiomatically with to_enum:very_large_string.to_enum(:split,"|").lazy.grep(/DATE/).first

It is typical to callto_enum when defining methods for a genericEnumerable, in case no block is passed.

Here is such an example, with parameter passing and a sizing block:

moduleEnumerable# a generic method to repeat the values of any enumerabledefrepeat(n)raiseArgumentError,"#{n} is negative!"ifn<0unlessblock_given?returnto_enum(__method__,n)do# __method__ is :repeat heresz =size# Call size and multiply by n...sz*nifsz# but return nil if size itself is nilendendeachdo|*val|n.times {yield*val }endendend%i[hello world].repeat(2) {|w|putsw }# => Prints 'hello', 'hello', 'world', 'world'enum = (1..14).repeat(3)# => returns an Enumerator when called without a blockenum.first(4)# => [1, 1, 1, 2]enum.size# => 42

VALUErb_obj_equal(VALUE obj1, VALUE obj2){    return RBOOL(obj1 == obj2);}

Equality — At theObject level,== returnstrue only ifobj andother are the same object. Typically, this method is overridden in descendant classes to provide class-specific meaning.

Unlike==, theequal? method should never be overridden by subclasses as it is used to determine object identity (that is,a.equal?(b) if and only ifa is the same object asb):

obj ="a"other =obj.dupobj==other#=> trueobj.equal?other#=> falseobj.equal?obj#=> true

Theeql? method returnstrue ifobj andother refer to the same hash key. This is used byHash to test members for equality. For any pair of objects whereeql? returnstrue, thehash value of both objects must be equal. So any subclass that overrideseql? should also overridehash appropriately.

For objects of classObject,eql? is synonymous with==. Subclasses normally continue this tradition by aliasingeql? to their overridden== method, but there are exceptions.Numeric types, for example, perform type conversion across==, but not acrosseql?, so:

1==1.0#=> true1.eql?1.0#=> false

static VALUErb_obj_extend(int argc, VALUE *argv, VALUE obj){    int i;    ID id_extend_object, id_extended;    CONST_ID(id_extend_object, "extend_object");    CONST_ID(id_extended, "extended");    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);    for (i = 0; i < argc; i++) {        Check_Type(argv[i], T_MODULE);        if (FL_TEST(argv[i], RMODULE_IS_REFINEMENT)) {            rb_raise(rb_eTypeError, "Cannot extend object with refinement");        }    }    while (argc--) {        rb_funcall(argv[argc], id_extend_object, 1, obj);        rb_funcall(argv[argc], id_extended, 1, obj);    }    return obj;}

Adds toobj the instance methods from each module given as a parameter.

moduleModdefhello"Hello from Mod.\n"endendclassKlassdefhello"Hello from Klass.\n"endendk =Klass.newk.hello#=> "Hello from Klass.\n"k.extend(Mod)#=> #<Klass:0x401b3bc8>k.hello#=> "Hello from Mod.\n"

VALUErb_obj_freeze(VALUE obj){    if (!OBJ_FROZEN(obj)) {        OBJ_FREEZE(obj);        if (SPECIAL_CONST_P(obj)) {            rb_bug("special consts should be frozen.");        }    }    return obj;}

Prevents further modifications toobj. AFrozenError will be raised if modification is attempted. There is no way to unfreeze a frozen object. See alsoObject#frozen?.

This method returns self.

a = ["a","b","c" ]a.freezea<<"z"

produces:

prog.rb:3:in `<<': can't modify frozen Array (FrozenError) from prog.rb:3

Objects of the following classes are always frozen:Integer,Float,Symbol.

VALUErb_obj_hash(VALUE obj){    long hnum = any_hash(obj, objid_hash);    return ST2FIX(hnum);}

Returns the integer hash value forself; has the property that iffoo.eql?(bar) thenfoo.hash == bar.hash.

ClassHash uses bothhash andeql? to determine whether two objects used as hash keys are to be treated as the same key. A hash value that exceeds the capacity of anInteger is truncated before being used.

Many core classes override methodObject#hash; other core classes (e.g.,Integer) calculate the hash internally, and do not call thehash method when used as a hash key.

When implementinghash for a user-defined class, best practice is to useArray#hash with the class name and the values that are important in the instance; this takes advantage of that method’s logic for safely and efficiently generating a hash value:

defhash  [self.class,a,b,c].hashend

The hash value may differ among invocations or implementations of Ruby. If you need stable hash-like identifiers across Ruby invocations and implementations, use a custom method to generate them.

static VALUErb_obj_inspect(VALUE obj){    VALUE ivars = rb_check_funcall(obj, id_instance_variables_to_inspect, 0, 0);    st_index_t n = 0;    if (UNDEF_P(ivars)) {        n = rb_ivar_count(obj);        ivars = Qnil;    }    else if (!NIL_P(ivars)) {        Check_Type(ivars, T_ARRAY);        n = RARRAY_LEN(ivars);    }    if (n > 0) {        VALUE c = rb_class_name(CLASS_OF(obj));        VALUE args[2] = {            rb_sprintf("-<%"PRIsVALUE":%p", c, (void*)obj),            ivars        };        return rb_exec_recursive(inspect_obj, obj, (VALUE)args);    }    else {        return rb_any_to_s(obj);    }}

Returns a string containing a human-readable representation ofobj. The defaultinspect shows the object’s class name, an encoding of its memory address, and a list of the instance variables and their values (by callinginspect on each of them). User defined classes should override this method to provide a better representation ofobj. When overriding this method, it should return a string whose encoding is compatible with the default external encoding.

[1,2,3..4,'five' ].inspect#=> "[1, 2, 3..4, \"five\"]"Time.new.inspect#=> "2008-03-08 19:43:39 +0900"classFooendFoo.new.inspect#=> "#<Foo:0x0300c868>"classBardefinitialize@bar =1endendBar.new.inspect#=> "#<Bar:0x0300c868 @bar=1>"

Ifobj responds toinstance_variables_to_inspect, then only the instance variables listed in the returned array will be included in the inspect string.

classDatabaseConfigdefinitialize(host,user,password)@host =host@user =user@password =passwordendprivatedefinstance_variables_to_inspect = [:@host,:@user]endconf =DatabaseConfig.new("localhost","root","hunter2")conf.inspect#=> #<DatabaseConfig:0x0000000104def350 @host="localhost", @user="root">

VALUErb_obj_is_instance_of(VALUE obj, VALUE c){    c = class_or_module_required(c);    return RBOOL(rb_obj_class(obj) == c);}

Returnstrue ifobj is an instance of the given class. See alsoObject#kind_of?.

classA;endclassB<A;endclassC<B;endb =B.newb.instance_of?A#=> falseb.instance_of?B#=> trueb.instance_of?C#=> false

static VALUErb_obj_ivar_defined(VALUE obj, VALUE iv){    ID id = id_for_var(obj, iv, instance);    if (!id) {        return Qfalse;    }    return rb_ivar_defined(obj, id);}

Returnstrue if the given instance variable is defined inobj.String arguments are converted to symbols.

classFreddefinitialize(p1,p2)@a,@b =p1,p2endendfred =Fred.new('cat',99)fred.instance_variable_defined?(:@a)#=> truefred.instance_variable_defined?("@b")#=> truefred.instance_variable_defined?("@c")#=> false

static VALUErb_obj_ivar_get(VALUE obj, VALUE iv){    ID id = id_for_var(obj, iv, instance);    if (!id) {        return Qnil;    }    return rb_ivar_get(obj, id);}

Returns the value of the given instance variable, or nil if the instance variable is not set. The@ part of the variable name should be included for regular instance variables. Throws aNameError exception if the supplied symbol is not valid as an instance variable name.String arguments are converted to symbols.

classFreddefinitialize(p1,p2)@a,@b =p1,p2endendfred =Fred.new('cat',99)fred.instance_variable_get(:@a)#=> "cat"fred.instance_variable_get("@b")#=> 99

static VALUErb_obj_ivar_set_m(VALUE obj, VALUE iv, VALUE val){    ID id = id_for_var(obj, iv, instance);    if (!id) id = rb_intern_str(iv);    return rb_ivar_set(obj, id, val);}

Sets the instance variable named bysymbol to the given object. This may circumvent the encapsulation intended by the author of the class, so it should be used with care. The variable does not have to exist prior to this call. If the instance variable name is passed as a string, that string is converted to a symbol.

classFreddefinitialize(p1,p2)@a,@b =p1,p2endendfred =Fred.new('cat',99)fred.instance_variable_set(:@a,'dog')#=> "dog"fred.instance_variable_set(:@c,'cat')#=> "cat"fred.inspect#=> "#<Fred:0x401b3da8 @a=\"dog\", @b=99, @c=\"cat\">"

VALUErb_obj_instance_variables(VALUE obj){    VALUE ary;    ary = rb_ary_new();    rb_ivar_foreach(obj, ivar_i, ary);    return ary;}

Returns an array of instance variable names for the receiver. Note that simply defining an accessor does not create the corresponding instance variable.

classFredattr_accessor:a1definitialize@iv =3endendFred.new.instance_variables#=> [:@iv]

Returnstrue ifclass is the class ofobj, or ifclass is one of the superclasses ofobj or modules included inobj.

moduleM;endclassAincludeMendclassB<A;endclassC<B;endb =B.newb.is_a?A#=> trueb.is_a?B#=> trueb.is_a?C#=> falseb.is_a?M#=> trueb.kind_of?A#=> trueb.kind_of?B#=> trueb.kind_of?C#=> falseb.kind_of?M#=> true

static VALUErb_obj_itself(VALUE obj){    return obj;}

Returns the receiver.

string ="my string"string.itself.object_id==string.object_id#=> true

VALUErb_obj_is_kind_of(VALUE obj, VALUE c){    VALUE cl = CLASS_OF(obj);    RUBY_ASSERT(RB_TYPE_P(cl, T_CLASS));    // Fastest path: If the object's class is an exact match we know `c` is a    // class without checking type and can return immediately.    if (cl == c) return Qtrue;    // Note: YJIT needs this function to never allocate and never raise when    // `c` is a class or a module.    if (LIKELY(RB_TYPE_P(c, T_CLASS))) {        // Fast path: Both are T_CLASS        return class_search_class_ancestor(cl, c);    }    else if (RB_TYPE_P(c, T_ICLASS)) {        // First check if we inherit the includer        // If we do we can return true immediately        VALUE includer = RCLASS_INCLUDER(c);        if (cl == includer) return Qtrue;        // Usually includer is a T_CLASS here, except when including into an        // already included Module.        // If it is a class, attempt the fast class-to-class check and return        // true if there is a match.        if (RB_TYPE_P(includer, T_CLASS) && class_search_class_ancestor(cl, includer))            return Qtrue;        // We don't include the ICLASS directly, so must check if we inherit        // the module via another include        return RBOOL(class_search_ancestor(cl, RCLASS_ORIGIN(c)));    }    else if (RB_TYPE_P(c, T_MODULE)) {        // Slow path: check each ancestor in the linked list and its method table        return RBOOL(class_search_ancestor(cl, RCLASS_ORIGIN(c)));    }    else {        rb_raise(rb_eTypeError, "class or module required");        UNREACHABLE_RETURN(Qfalse);    }}

Returnstrue ifclass is the class ofobj, or ifclass is one of the superclasses ofobj or modules included inobj.

moduleM;endclassAincludeMendclassB<A;endclassC<B;endb =B.newb.is_a?A#=> trueb.is_a?B#=> trueb.is_a?C#=> falseb.is_a?M#=> trueb.kind_of?A#=> trueb.kind_of?B#=> trueb.kind_of?C#=> falseb.kind_of?M#=> true

VALUErb_obj_method(VALUE obj, VALUE vid){    return obj_method(obj, vid, FALSE);}

Looks up the named method as a receiver inobj, returning aMethod object (or raisingNameError). TheMethod object acts as a closure inobj’s object instance, so instance variables and the value ofself remain available.

classDemodefinitialize(n)@iv =nenddefhello()"Hello, @iv = #{@iv}"endendk =Demo.new(99)m =k.method(:hello)m.call#=> "Hello, @iv = 99"l =Demo.new('Fred')m =l.method("hello")m.call#=> "Hello, @iv = Fred"

Note thatMethod implementsto_proc method, which means it can be used with iterators.

[1,2,3 ].each(&method(:puts))# => prints 3 lines to stdoutout =File.open('test.txt','w')[1,2,3 ].each(&out.method(:puts))# => prints 3 lines to filerequire'date'%w[2017-03-01 2017-03-02].collect(&Date.method(:parse))#=> [#<Date: 2017-03-01 ((2457814j,0s,0n),+0s,2299161j)>, #<Date: 2017-03-02 ((2457815j,0s,0n),+0s,2299161j)>]

VALUErb_obj_methods(int argc, const VALUE *argv, VALUE obj){    rb_check_arity(argc, 0, 1);    if (argc > 0 && !RTEST(argv[0])) {        return rb_obj_singleton_methods(argc, argv, obj);    }    return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_i);}

Returns a list of the names of public and protected methods ofobj. This will include all the methods accessible inobj’s ancestors. If the optional parameter isfalse, it returns an array ofobj’s public and protected singleton methods, the array will not include methods in modules included inobj.

classKlassdefklass_method()endendk =Klass.newk.methods[0..9]#=> [:klass_method, :nil?, :===,#    :==~, :!, :eql?#    :hash, :<=>, :class, :singleton_class]k.methods.length#=> 56k.methods(false)#=> []defk.singleton_method;endk.methods(false)#=> [:singleton_method]moduleM123;defm123;endendk.extendM123k.methods(false)#=> [:singleton_method]

VALUErb_false(VALUE obj){    return Qfalse;}

Only the objectnil respondstrue tonil?.

Object.new.nil?#=> falsenil.nil?#=> true

VALUErb_obj_id(VALUE obj){    /* If obj is an immediate, the object ID is obj directly converted to a Numeric.     * Otherwise, the object ID is a Numeric that is a non-zero multiple of     * (RUBY_IMMEDIATE_MASK + 1) which guarantees that it does not collide with     * any immediates. */    return rb_find_object_id(rb_gc_get_objspace(), obj, object_id);}

Returns an integer identifier forobj.

The same number will be returned on all calls toobject_id for a given object, and no two active objects will share an id.

Note: that some objects of builtin classes are reused for optimization. This is the case for immediate values and frozen string literals.

BasicObject implements__id__,Kernel implementsobject_id.

Immediate values are not passed by reference but are passed by value:nil,true,false, Fixnums, Symbols, and some Floats.

Object.new.object_id==Object.new.object_id# => false(21*2).object_id== (21*2).object_id# => true"hello".object_id=="hello".object_id# => false"hi".freeze.object_id=="hi".freeze.object_id# => true

VALUErb_obj_private_methods(int argc, const VALUE *argv, VALUE obj){    return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_priv_i);}

Returns the list of private methods accessible toobj. If theall parameter is set tofalse, only those methods in the receiver will be listed.

VALUErb_obj_protected_methods(int argc, const VALUE *argv, VALUE obj){    return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_prot_i);}

Returns the list of protected methods accessible toobj. If theall parameter is set tofalse, only those methods in the receiver will be listed.

VALUErb_obj_public_method(VALUE obj, VALUE vid){    return obj_method(obj, vid, TRUE);}

Similar tomethod, searches public method only.

VALUErb_obj_public_methods(int argc, const VALUE *argv, VALUE obj){    return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_pub_i);}

Returns the list of public methods accessible toobj. If theall parameter is set tofalse, only those methods in the receiver will be listed.

static VALUErb_f_public_send(int argc, VALUE *argv, VALUE recv){    return send_internal_kw(argc, argv, recv, CALL_PUBLIC);}

Invokes the method identified bysymbol, passing it any arguments specified. Unlike send,public_send calls public methods only. When the method is identified by a string, the string is converted to a symbol.

1.public_send(:puts,"hello")# causes NoMethodError

VALUErb_obj_remove_instance_variable(VALUE obj, VALUE name){    const ID id = id_for_var(obj, name, an, instance);    // Frozen check comes here because it's expected that we raise a    // NameError (from the id_for_var check) before we raise a FrozenError    rb_check_frozen(obj);    if (id) {        VALUE val = rb_ivar_delete(obj, id, Qundef);        if (!UNDEF_P(val)) return val;    }    rb_name_err_raise("instance variable %1$s not defined",                      obj, name);    UNREACHABLE_RETURN(Qnil);}

Removes the named instance variable fromobj, returning that variable’s value. The name can be passed as a symbol or as a string.

classDummyattr_reader:vardefinitialize@var =99enddefremoveremove_instance_variable(:@var)endendd =Dummy.newd.var#=> 99d.remove#=> 99d.var#=> nil

static VALUEobj_respond_to(int argc, VALUE *argv, VALUE obj){    VALUE mid, priv;    ID id;    rb_execution_context_t *ec = GET_EC();    rb_scan_args(argc, argv, "11", &mid, &priv);    if (!(id = rb_check_id(&mid))) {        VALUE ret = basic_obj_respond_to_missing(ec, CLASS_OF(obj), obj,                                                 rb_to_symbol(mid), priv);        if (UNDEF_P(ret)) ret = Qfalse;        return ret;    }    return  RBOOL(basic_obj_respond_to(ec, obj, id, !RTEST(priv)));}

Returnstrue ifobj responds to the given method. Private and protected methods are included in the search only if the optional second parameter evaluates totrue.

If the method is not implemented, asProcess.fork on Windows,File.lchmod on GNU/Linux, etc., false is returned.

If the method is not defined,respond_to_missing? method is called and the result is returned.

When the method name parameter is given as a string, the string is converted to a symbol.

static VALUEobj_respond_to_missing(VALUE obj, VALUE mid, VALUE priv){    return Qfalse;}

DO NOT USE THIS DIRECTLY.

Hook method to return whether theobj can respond toid method or not.

When the method name parameter is given as a string, the string is converted to a symbol.

Seerespond_to?, and the example ofBasicObject.

VALUErb_f_send(int argc, VALUE *argv, VALUE recv){    return send_internal_kw(argc, argv, recv, CALL_FCALL);}

Invokes the method identified bysymbol, passing it any arguments specified. When the method is identified by a string, the string is converted to a symbol.

BasicObject implements__send__,Kernel implementssend.__send__ is safer thansend whenobj has the same method name likeSocket. See alsopublic_send.

classKlassdefhello(*args)"Hello "+args.join(' ')endendk =Klass.newk.send:hello,"gentle","readers"#=> "Hello gentle readers"

static VALUErb_obj_singleton_class(VALUE obj){    return rb_singleton_class(obj);}

Returns the singleton class ofobj. This method creates a new singleton class ifobj does not have one.

Ifobj isnil,true, orfalse, it returnsNilClass,TrueClass, orFalseClass, respectively. Ifobj is anInteger, aFloat or aSymbol, it raises aTypeError.

Object.new.singleton_class#=> #<Class:#<Object:0xb7ce1e24>>String.singleton_class#=> #<Class:String>nil.singleton_class#=> NilClass

VALUErb_obj_singleton_method(VALUE obj, VALUE vid){    VALUE sc = rb_singleton_class_get(obj);    VALUE klass;    ID id = rb_check_id(&vid);    if (NIL_P(sc) ||        NIL_P(klass = RCLASS_ORIGIN(sc)) ||        !NIL_P(rb_special_singleton_class(obj))) {        /* goto undef; */    }    else if (! id) {        VALUE m = mnew_missing_by_name(klass, obj, &vid, FALSE, rb_cMethod);        if (m) return m;        /* else goto undef; */    }    else {        VALUE args[2] = {obj, vid};        VALUE ruby_method = rb_rescue(rb_obj_singleton_method_lookup, (VALUE)args, rb_obj_singleton_method_lookup_fail, Qfalse);        if (ruby_method) {            struct METHOD *method = (struct METHOD *)RTYPEDDATA_GET_DATA(ruby_method);            VALUE lookup_class = RBASIC_CLASS(obj);            VALUE stop_class = rb_class_superclass(sc);            VALUE method_class = method->iclass;            /* Determine if method is in singleton class, or module included in or prepended to it */            do {                if (lookup_class == method_class) {                    return ruby_method;                }                lookup_class = RCLASS_SUPER(lookup_class);            } while (lookup_class && lookup_class != stop_class);        }    }  /* undef: */    vid = ID2SYM(id);    rb_name_err_raise("undefined singleton method '%1$s' for '%2$s'",                      obj, vid);    UNREACHABLE_RETURN(Qundef);}

Similar tomethod, searches singleton method only.

classDemodefinitialize(n)@iv =nenddefhello()"Hello, @iv = #{@iv}"endendk =Demo.new(99)defk.hi"Hi, @iv = #{@iv}"endm =k.singleton_method(:hi)m.call#=> "Hi, @iv = 99"m =k.singleton_method(:hello)#=> NameError

VALUErb_obj_singleton_methods(int argc, const VALUE *argv, VALUE obj){    VALUE ary, klass, origin;    struct method_entry_arg me_arg;    struct rb_id_table *mtbl;    int recur = TRUE;    if (rb_check_arity(argc, 0, 1)) recur = RTEST(argv[0]);    if (RCLASS_SINGLETON_P(obj)) {        rb_singleton_class(obj);    }    klass = CLASS_OF(obj);    origin = RCLASS_ORIGIN(klass);    me_arg.list = st_init_numtable();    me_arg.recur = recur;    if (klass && RCLASS_SINGLETON_P(klass)) {        if ((mtbl = RCLASS_M_TBL(origin)) != 0) rb_id_table_foreach(mtbl, method_entry_i, &me_arg);        klass = RCLASS_SUPER(klass);    }    if (recur) {        while (klass && (RCLASS_SINGLETON_P(klass) || RB_TYPE_P(klass, T_ICLASS))) {            if (klass != origin && (mtbl = RCLASS_M_TBL(klass)) != 0) rb_id_table_foreach(mtbl, method_entry_i, &me_arg);            klass = RCLASS_SUPER(klass);        }    }    ary = rb_ary_new2(me_arg.list->num_entries);    st_foreach(me_arg.list, ins_methods_i, ary);    st_free_table(me_arg.list);    return ary;}

Returns an array of the names of singleton methods forobj. If the optionalall parameter is true, the list will include methods in modules included inobj. Only public and protected singleton methods are returned.

moduleOtherdefthree()endendclassSingledefSingle.four()endenda =Single.newdefa.one()endclass<<aincludeOtherdeftwo()endendSingle.singleton_methods#=> [:four]a.singleton_methods(false)#=> [:two, :one]a.singleton_methods#=> [:two, :one, :three]

static VALUEobj_to_enum(int argc, VALUE *argv, VALUE obj){    VALUE enumerator, meth = sym_each;    if (argc > 0) {        --argc;        meth = *argv++;    }    enumerator = rb_enumeratorize_with_size(obj, meth, argc, argv, 0);    if (rb_block_given_p()) {        RB_OBJ_WRITE(enumerator, &enumerator_ptr(enumerator)->size, rb_block_proc());    }    return enumerator;}

Creates a newEnumerator which will enumerate by callingmethod onobj, passingargs if any. What wasyielded by method becomes values of enumerator.

If a block is given, it will be used to calculate the size of the enumerator without the need to iterate it (seeEnumerator#size).

Examples¶↑

str ="xyz"enum =str.enum_for(:each_byte)enum.each {|b|putsb }# => 120# => 121# => 122# protect an array from being modified by some_methoda = [1,2,3]some_method(a.to_enum)# String#split in block form is more memory-effective:very_large_string.split("|") {|chunk|returnchunkifchunk.include?('DATE') }# This could be rewritten more idiomatically with to_enum:very_large_string.to_enum(:split,"|").lazy.grep(/DATE/).first

It is typical to callto_enum when defining methods for a genericEnumerable, in case no block is passed.

Here is such an example, with parameter passing and a sizing block:

moduleEnumerable# a generic method to repeat the values of any enumerabledefrepeat(n)raiseArgumentError,"#{n} is negative!"ifn<0unlessblock_given?returnto_enum(__method__,n)do# __method__ is :repeat heresz =size# Call size and multiply by n...sz*nifsz# but return nil if size itself is nilendendeachdo|*val|n.times {yield*val }endendend%i[hello world].repeat(2) {|w|putsw }# => Prints 'hello', 'hello', 'world', 'world'enum = (1..14).repeat(3)# => returns an Enumerator when called without a blockenum.first(4)# => [1, 1, 1, 2]enum.size# => 42

VALUErb_any_to_s(VALUE obj){    VALUE str;    VALUE cname = rb_class_name(CLASS_OF(obj));    str = rb_sprintf("#<%"PRIsVALUE":%p>", cname, (void*)obj);    return str;}

Returns a string representingobj. The defaultto_s prints the object’s class and an encoding of the object id. As a special case, the top-level object that is the initial execution context of Ruby programs returns “main”.

# File ext/psych/lib/psych/core_ext.rb, line 12defto_yamloptions = {}Psych.dumpself,optionsend

Convert an object toYAML. SeePsych.dump for more information on the availableoptions.