# A 'require' question **URL:** \ **Category:** Ruby\ **Created:** [January 6, 2007, 7:31pm UTC](https://www.ruby-forum.com/t/a-require-question/81279 "2007-01-06T19:31:00Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![bbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/97f17d/32.png) [@bbiker](https://www.ruby-forum.com/u/bbiker)\ **Post date:** [January 6, 2007, 7:31pm UTC](https://www.ruby-forum.com/t/a-require-question/81279/1 "2007-01-06T19:31:00Z")
When you have multiple versions of a gem, “require ‘gemxxx’” loads in the latest version. How can you specify a specific version (or some other constraint)? The ri documentation for require is of no help. * * * ## Kernel#require require(string) =\> true or false Ruby tries to load the library named _string_, returning +true+ if successful. If the filename does not resolve to an absolute path, it will be searched for in the directories listed in +$:+. If the file has the extension `.rb'', it is loaded as a source file; if the extension is`.so’’, `.o'', or`.dll’’, or whatever the default shared library extension is on the current platform, Ruby loads the shared library as a Ruby extension. Otherwise, Ruby tries adding `.rb'',`.so’’, and so on to the name. The name of the loaded feature is added to the array in +$"+. A feature will not be loaded if it’s name already appears in +$"+. However, the file name is not converted to an absolute path, so that ``+require ‘a’;require ‘./a’+’’ will load +a.rb+ twice. ``` require "my-library.rb" require "db-driver" ``` ---
**Author:** ![bbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/97f17d/32.png) [@bbiker](https://www.ruby-forum.com/u/bbiker)\ **Post date:** [January 19, 2007, 4:30pm UTC](https://www.ruby-forum.com/t/a-require-question/81279/2 "2007-01-19T16:30:00Z")
require\_gem ‘gem\_name’, ‘\>=1.2.3’ Though newest version of gems now has just gem ‘gem\_name’, ‘\>=1.2.3’ Jason ---
**Author:** ![bbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/97f17d/32.png) [@bbiker](https://www.ruby-forum.com/u/bbiker)\ **Post date:** [January 19, 2007, 4:30pm UTC](https://www.ruby-forum.com/t/a-require-question/81279/3 "2007-01-19T16:30:21Z")
On Jan 5, 2007, at 09:45, bbiker wrote: > When you have multiple versions of a gem, “require ‘gemxxx’” loads in > the latest version. > > How can you specify a specific version (or some other constraint)? gem ‘gemname’, ‘= 1.2.3’ # \<, \<=, =, \>= and \> are all understood require ‘the\_file\_you\_want’ > The ri documentation for require is of no help. RubyGems will build and install RDoc and ri for itself in the next release. – Eric H. - removed\_email\_address@domain.invalid - [http://blog.segment7.net](http://blog.segment7.net) I LIT YOUR GEM ON FIRE! ---
**Author:** ![bbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/97f17d/32.png) [@bbiker](https://www.ruby-forum.com/u/bbiker)\ **Post date:** [September 25, 2007, 10:32pm UTC](https://www.ruby-forum.com/t/a-require-question/81279/4 "2007-09-25T22:32:46Z")
On Jan 5, 2007, at 10:57, Jason R. wrote: > On 1/5/07, bbiker [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > When you have multiple versions of a gem, “require ‘gemxxx’” loads in > > the latest version. > > > > How can you specify a specific version (or some other constraint)? > > require\_gem ‘gem\_name’, ‘\>=1.2.3’ require\_gem was deprecated in 0.9.0. Switch to ‘gem’, don’t recommend its use. > Though newest version of gems now has just > > gem ‘gem\_name’, ‘\>=1.2.3’ – Eric H. - removed\_email\_address@domain.invalid - [http://blog.segment7.net](http://blog.segment7.net) A: Yes Q: Is top-posting bad? — Derek Milhous Zumsteg ---
**Author:** ![bbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/97f17d/32.png) [@bbiker](https://www.ruby-forum.com/u/bbiker)\ **Post date:** [September 25, 2007, 10:40pm UTC](https://www.ruby-forum.com/t/a-require-question/81279/5 "2007-09-25T22:40:38Z")
On 1/5/07, bbiker [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I meant how do you specify a version or other constraints with > “require” > > for example: > require ‘gem\_name’ > > require can only take one parameter > > thus require ‘gem\_name’, ‘\>=1.23’ responds with: you need three commands: 1. require ‘rubygems’ # may be omitted when RUBYOPT=-rubygems or ruby is started with -rubygems 2. gem ‘gem\_name’ , ‘\>=1.23’ # this sets the required version and this is what eric wrote about 3. require ‘gem\_name’ # to actually require the file - no version or anything Actually the gem\_name in he steps 2. and 3. may be different - one is the name of the gem (win32-shortcut for example) while the latter is the name of the file to be required (win32/shortcut) If and only if you’ll see undefined method ‘gem’ in the second step, then replace ‘gem’ with ‘require\_gem’ (meaning you have an old version of rubygems, and you might want to upgrade) ---
**Author:** ![bbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/97f17d/32.png) [@bbiker](https://www.ruby-forum.com/u/bbiker)\ **Post date:** [September 25, 2007, 10:48pm UTC](https://www.ruby-forum.com/t/a-require-question/81279/6 "2007-09-25T22:48:35Z")
On Jan 5, 2007, at 13:45, bbiker wrote: > Eric H. wrote: > > > On Jan 5, 2007, at 10:57, Jason R. wrote: > > > > > Though newest version of gems now has just > > > > > > gem ‘gem\_name’, ‘\>=1.2.3’ > > Sorry, I think I posed my question badly. > > I meant how do you specify a version or other constraints with > “require” You can’t. You use #gem instead of #require. > LoadError: no such file to load – gem\_name \>=1.23 > > yes, I did use a gem name that I had on my machine No, you didn’t. There is no ‘zentest’ gem. > I tried in irb: > gem ‘zentest’, ‘\>=3.4.3’, response was > Gem::LoadError: Could not find RubyGem zentest \<\>=3.4.3 > > gem ‘zentest’ response was > Gem::LoadError: Could not find RubyGem zentest \<\>=0.0.0 Since RubyGems couldn’t find a ‘zentest’ gem, you must not have it installed. There is a ‘ZenTest’ gem, though: $ gem list -r zentest \*\*\* REMOTE GEMS \*\*\* Bulk updating Gem source index for: [http://gems.rubyforge.org](http://gems.rubyforge.org) ZenTest (3.4.3, 3.4.2, 3.4.1, 3.4.0, 3.3.0, 3.2.0, 3.1.0, 3.0.0) ZenTest provides 4 different tools and 1 library: zentest, unit\_diff, autotest, multiruby, and Test::Rails. ^^^^^^^ capitalization matters. – Eric H. - removed\_email\_address@domain.invalid - [http://blog.segment7.net](http://blog.segment7.net) I LIT YOUR GEM ON FIRE! ---
**Author:** ![bbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/97f17d/32.png) [@bbiker](https://www.ruby-forum.com/u/bbiker)\ **Post date:** [September 25, 2007, 10:49pm UTC](https://www.ruby-forum.com/t/a-require-question/81279/7 "2007-09-25T22:49:32Z")
Eric H. wrote: > On Jan 5, 2007, at 10:57, Jason R. wrote: > > Though newest version of gems now has just > > > > gem ‘gem\_name’, ‘\>=1.2.3’ Sorry, I think I posed my question badly. I meant how do you specify a version or other constraints with “require” for example: require ‘gem\_name’ require can only take one parameter thus require ‘gem\_name’, ‘\>=1.23’ responds with: ArgumentError: wrong number of arguments (2 for 1) and require ‘gem\_name \>=1.23’ responds with LoadError: no such file to load – gem\_name \>=1.23 yes, I did use a gem name that I had on my machine I tried in irb: gem ‘zentest’, ‘\>=3.4.3’, response was Gem::LoadError: Could not find RubyGem zentest \<\>=3.4.3 gem ‘zentest’ response was Gem::LoadError: Could not find RubyGem zentest \<\>=0.0.0 I have gem 0.9.0 and ruby 1.8.5 on Windows ---
**Author:** ![bbiker](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/97f17d/32.png) [@bbiker](https://www.ruby-forum.com/u/bbiker)\ **Post date:** [September 25, 2007, 10:50pm UTC](https://www.ruby-forum.com/t/a-require-question/81279/8 "2007-09-25T22:50:40Z")
Jan S. wrote: > Actually the gem\_name in he steps 2. and 3. may be different - one is > the name of the gem (win32-shortcut for example) while the latter is > the name of the file to be required (win32/shortcut) > > If and only if you’ll see undefined method ‘gem’ in the second step, > then replace ‘gem’ with ‘require\_gem’ (meaning you have an old version > of rubygems, and you might want to upgrade) Thank you all for your responses. I now have a clearer understanding of ‘require’ and ‘gem’ and how they cooperate.