# Given a string find the matching class **URL:** \ **Category:** Ruby\ **Created:** [December 9, 2008, 11:13pm UTC](https://www.ruby-forum.com/t/given-a-string-find-the-matching-class/155263 "2008-12-09T23:13:22Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![byrnejb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/d2c977/32.png) [@byrnejb](https://www.ruby-forum.com/u/byrnejb)\ **Post date:** [December 9, 2008, 11:13pm UTC](https://www.ruby-forum.com/t/given-a-string-find-the-matching-class/155263/1 "2008-12-09T23:13:22Z")
I have a situation where I desire to pass a string to a method that then: 1. Capitalizes the the string value 2. Finds a class by that name Something like: def findmyclass(m) find\_class\_by\_name(m.capitalize) end Is this possible (surely) and if so, how is it done? Thanks ---
**Author:** ![byrnejb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/d2c977/32.png) [@byrnejb](https://www.ruby-forum.com/u/byrnejb)\ **Post date:** [December 10, 2008, 2:12am UTC](https://www.ruby-forum.com/t/given-a-string-find-the-matching-class/155263/2 "2008-12-10T02:12:21Z")
On Wed, Dec 10, 2008 at 6:06 AM, James B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I have a situation where I desire to pass a string to a method that > then: > > 1. Capitalizes the the string value > 2. Finds a class by that name > Something like: > def findmyclass(m) > find\_class\_by\_name(m.capitalize) > end > Is this possible (surely) and if so, how is it done? 1 class names are constants, thus 1.1 they start w upcase, and 1.2 are case sensitive 2 you get the value of a quoted/stringified constant by using const\_get 3 you can then check the value returned by checking if it #is\_a? Class eg, > Object.const\_get(“XX”).is\_a? Class > =\> true > Object.const\_get(“Xx”).is\_a? Class > =\> true > Object.const\_get(“YY”) > NameError: uninitialized constant YY now, if you want to find classes tucked in on other modules/classes, you’ll have to scan the whole ObjectSpace; eg, looking for a class named “C” wc is in “A:🅱:C”… eg, > ObjectSpace.each\_object(Class).each {|x| p x if x.name =~ /^M/ } > Method > MatchData > Module > M::MM ---
**Author:** ![byrnejb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/d2c977/32.png) [@byrnejb](https://www.ruby-forum.com/u/byrnejb)\ **Post date:** [December 10, 2008, 9:07pm UTC](https://www.ruby-forum.com/t/given-a-string-find-the-matching-class/155263/3 "2008-12-10T21:07:54Z")
botp wrote: > 3 you can then check the value returned by checking if it #is\_a? Class > … > > > Object.const\_get(“XX”).is\_a? Class > > =\> true > > Object.const\_get(“Xx”).is\_a? Class > > =\> true > > Object.const\_get(“YY”) > > NameError: uninitialized constant YY > > now, if you want to find classes tucked in on other modules/classes, > you’ll have to scan the whole ObjectSpace; eg, looking for a class > named “C” wc is in “A:🅱:C”… > … > ObjectSpace.each\_object(Class).each {|x| p x if x.name =~ /^M/ } > Method > MatchData > Module > M::MM Many thanks for this lucid explanation.