# Newbie question about the # symbol **URL:** \ **Category:** Ruby\ **Created:** [March 14, 2006, 2:20pm UTC](https://www.ruby-forum.com/t/newbie-question-about-the-symbol/54801 "2006-03-14T14:20:17Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![justin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/3ab097/32.png) [@justin](https://www.ruby-forum.com/u/justin)\ **Post date:** [March 14, 2006, 2:20pm UTC](https://www.ruby-forum.com/t/newbie-question-about-the-symbol/54801/1 "2006-03-14T14:20:17Z")
I have just started learning Ruby and I am going through as much documentation as I can find. The only question that I cannot seem to find an answer to concerns the use of the # symbol when referring to methods (I think I’ve seen it used to refer to both class and instance methods). Here is an example: [http://www.rubycentral.com/book/ref\_c\_io.html#IO.select](http://www.rubycentral.com/book/ref_c_io.html#IO.select) On the above page there is a link to “Kernel#select” which is a class method. and here: [http://www.rubycentral.com/book/ref\_c\_object.html#Object.is\_a\_qm](http://www.rubycentral.com/book/ref_c_object.html#Object.is_a_qm) There is a link to “Object#kind\_of?” which is an instance method. Clearly the purpose of the hash mark has another purpose. Anyone know what document explains this? Thanks! Justin ---
**Author:** ![justin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/3ab097/32.png) [@justin](https://www.ruby-forum.com/u/justin)\ **Post date:** [March 14, 2006, 2:34pm UTC](https://www.ruby-forum.com/t/newbie-question-about-the-symbol/54801/2 "2006-03-14T14:34:54Z")
# is not Ruby syntax, it’s a documentation convention that denotes “instance method,” as in “kind\_of? is an instance method of Object” as opposed to “class method,” which is distinguished by a period between the class name and the method name. ---
**Author:** ![justin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/3ab097/32.png) [@justin](https://www.ruby-forum.com/u/justin)\ **Post date:** [March 14, 2006, 2:35pm UTC](https://www.ruby-forum.com/t/newbie-question-about-the-symbol/54801/3 "2006-03-14T14:35:51Z")
Justin wrote: > There is a link to “Object#kind\_of?” which is an instance method. > Clearly the purpose of the hash mark has another purpose. Anyone know > what document explains this? The notation’s explained in the preface: [http://www.rubycentral.com/book/preface.html#S10](http://www.rubycentral.com/book/preface.html#S10) Basically it means “the instance method kind\_of? implemented by the Object class”; not really syntax, but convention for discussing Ruby. The ‘ri’ utility uses something similar. ---
**Author:** ![justin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/3ab097/32.png) [@justin](https://www.ruby-forum.com/u/justin)\ **Post date:** [March 14, 2006, 2:45pm UTC](https://www.ruby-forum.com/t/newbie-question-about-the-symbol/54801/4 "2006-03-14T14:45:55Z")
On Mar 14, 2006, at 7:33 AM, removed\_email\_address@domain.invalid wrote: > # is not Ruby syntax, it’s a documentation convention that denotes > > “instance method,” as in “kind\_of? is an instance method of Object” as > opposed to “class method,” which is distinguished by a period between > the class name and the method name. Class methods are also often shown as follows: MyClass::class\_method ri even seems to favor this notation. James Edward G. II ---
**Author:** ![justin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/3ab097/32.png) [@justin](https://www.ruby-forum.com/u/justin)\ **Post date:** [March 14, 2006, 2:45pm UTC](https://www.ruby-forum.com/t/newbie-question-about-the-symbol/54801/5 "2006-03-14T14:45:56Z")
On Mar 14, 2006, at 7:20 AM, Justin wrote: > Here is an example: > [http://www.rubycentral.com/book/ref\_c\_io.html#IO.select](http://www.rubycentral.com/book/ref_c_io.html#IO.select) > > On the above page there is a link to “Kernel#select” which is a class > method. Actually, all the Kernel methods are instance methods, so they can be mixed into Object. James Edward G. II ---
**Author:** ![justin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/3ab097/32.png) [@justin](https://www.ruby-forum.com/u/justin)\ **Post date:** [March 14, 2006, 2:46pm UTC](https://www.ruby-forum.com/t/newbie-question-about-the-symbol/54801/6 "2006-03-14T14:46:39Z")
Mike F. wrote: > Basically it means “the instance method kind\_of? implemented by the > Object class”; not really syntax, but convention for discussing Ruby. > The ‘ri’ utility uses something similar. Ahh ok, excellent thank you that was confusing me quite a bit.