# Ruby loops and definitions help? **URL:** \ **Category:** Ruby\ **Created:** [May 15, 2009, 11:21am UTC](https://www.ruby-forum.com/t/ruby-loops-and-definitions-help/168055 "2009-05-15T11:21:47Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![adistarmid](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/f14d63/32.png) [@adistarmid](https://www.ruby-forum.com/u/adistarmid)\ **Post date:** [May 15, 2009, 11:21am UTC](https://www.ruby-forum.com/t/ruby-loops-and-definitions-help/168055/1 "2009-05-15T11:21:47Z")
Hello. I’m looking to construct a loop that defines an array of [apple, banana, cherry] like this: @apple = apple @banana = banana @cherry = cherry I’m thinking it’s something in this form: [apple, banana, cherry].each do |attribute| @_attribute_ = attribute end …but I have no idea what belongs in place of the _attribute_. Does anyone know? ---
**Author:** ![adistarmid](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/f14d63/32.png) [@adistarmid](https://www.ruby-forum.com/u/adistarmid)\ **Post date:** [May 15, 2009, 11:51am UTC](https://www.ruby-forum.com/t/ruby-loops-and-definitions-help/168055/2 "2009-05-15T11:51:36Z")
Bob S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes: > @_attribute_ = attribute > end > > …but I have no idea what belongs in place of the _attribute_. Does > anyone know? Yes. The objects in ruby do know if and when, how. You must ask them! For example, using ri(1). irb(main):001:0\> (ri “Object”) ---------------------------------------------------------- Class: Object +Object+ is the parent class of all classes in Ruby. Its methods are therefore available to all objects unless explicitly overridden. ``` +Object+ mixes in the +Kernel+ module, making the built-in kernel functions globally accessible. Although the instance methods of +Object+ are defined by the +Kernel+ module, we have chosen to document them here for clarity. In the descriptions of Object's methods, the parameter _symbol_ refers to a symbol, which is either a quoted string or a +Symbol+ (such as +:name+). ``` * * * ## Includes: ``` Kernel(Array, Float, Integer, Pathname, String, URI, `, abort, at_exit, autoload, autoload?, binding, block_given?, callcc, caller, catch, chomp, chomp!, chop, chop!, eval, exec, exit, exit!, fail, fork, format, getc, gets, global_variables, gsub, gsub!, iterator?, lambda, load, local_variables, loop, method_missing, open, open, open_uri_original_open, p, pp, pretty_inspect, print, printf, proc, putc, puts, raise, rand, readline, readlines, require, scan, scanf, select, set_trace_func, sleep, split, sprintf, srand, sub, sub!, syscall, system, test, throw, trace_var, trap, untrace_var, warn, warn, y), PP::ObjectMixin(pretty_print, pretty_print_cycle, pretty_print_inspect, pretty_print_instance_variables) ``` ## Constants: ``` MatchingData: rb_cMatch ENV: envtbl ENV: envtbl TOPLEVEL_BINDING: rb_f_binding(ruby_top_self) STDIN: rb_stdin STDOUT: rb_stdout STDERR: rb_stderr ARGF: argf NIL: Qnil TRUE: Qtrue FALSE: Qfalse DATA: f ARGV: rb_argv RUBY_VERSION: v RUBY_RELEASE_DATE: d RUBY_PLATFORM: p RUBY_PATCHLEVEL: INT2FIX(RUBY_PATCHLEVEL) VERSION: v RELEASE_DATE: d PLATFORM: p IPsocket: rb_cIPSocket TCPsocket: rb_cTCPSocket SOCKSsocket: rb_cSOCKSSocket TCPserver: rb_cTCPServer UDPsocket: rb_cUDPSocket UNIXsocket: rb_cUNIXSocket UNIXserver: rb_cUNIXServer ``` ## Class methods: ``` new ``` ## Instance methods: ``` ==, ===, =~, __id__ , __send__ , class, clone, dclone, display, dup, enum_for, eql?, equal?, extend, freeze, frozen?, hash, id, inspect, instance_eval, instance_of?, instance_variable_get, instance_variable_get, instance_variable_set, instance_variable_set, instance_variables, is_a?, kind_of?, method, methods, nil?, object_id, private_methods, protected_methods, public_methods, remove_instance_variable, respond_to?, send, singleton_method_added, singleton_method_removed, singleton_method_undefined, singleton_methods, taint, tainted?, to_a, to_enum, to_s, to_yaml, to_yaml_properties, to_yaml_style, type, untaint ``` nil irb(main):002:0\> (ri “Object.instance\_variable\_set”) ## ------------------------------------------- Object#instance\_variable\_set obj.instance\_variable\_set(symbol, obj) =\> obj ``` Sets the instance variable names by _symbol_ to _object_, thereby frustrating the efforts of the class's author to attempt to provide proper encapsulation. The variable did not have to exist prior to this call. class Fred def initialize(p1, p2) @a, @b = p1, p2 end end fred = Fred.new('cat', 99) fred.instance_variable_set(:@a, 'dog') #=> "dog" fred.instance_variable_set(:@c, 'cat') #=> "cat" fred.inspect #=> "#" nil irb(main):003:0\> ( [“apple”,“banana”,“cherry”] . each { | attribute | (self . instance\_variable\_set( ((“@” + attribute) . to\_sym) , attribute)) } ) [“apple”, “banana”, “cherry”] irb(main):004:0\> @apple “apple” irb(main):005:0\> @banana “banana” irb(main):006:0\> @cherry “cherry” irb(main):007:0\> @pear nil irb(main):008:0\> That said, an array like [apple, banana, cherry] will actually be an array such as [“value of apple”, 42, [“the”,:value,0,“cherry”]]. If you want to build an array containing the name of the variable, then you have to make an array of symbols: [:apple,:banana,:cherry]. Then you will have to write: irb(main):018:0\> (begin (apple = “value of apple”) (banana = 42) (cherry = [“the”,:value,0,“cherry”]) ( [:apple,:banana,:cherry] . each { | variable | (self . instance\_variable\_set( ((“@” + (variable . to\_s)) . to\_sym) , (eval (variable . to\_s)))) }) end) [:apple, :banana, :cherry] irb(main):025:0\> @apple “value of apple” irb(main):026:0\> @banana 42 irb(main):027:0\> @cherry [“the”, :value, 0, “cherry”] irb(main):028:0\>