This is more a curiosity than necessity question. I've just installed nokogiri again with RubyGems and it is saying "WARNING: Nokogiri was built against LibXML version 2.7.5, but has dynamically loaded 2.7.6" This is easy enough to fix, but it lead to a more general question: how do I see all the configuration options for a rubygem before installing it?
I found the easiest way I know how is to visit the gem folder an run "ruby nokogiri-0.0.0/ext/nokogiri/extconf.rb -h" and that shows me it, but there has to be an easier way, right?
I was expecting some kind of "sudo gem install nokogiri -- --help" command that would show the build flags. I've searched around a bit but didn't see anything, anybody know how to do this before I go digging into RG's source :)?
Related
In our Rails application we do require 'RRD' at some point, but that results in a cannot load such file -- RRD. So obviously I used homebrew to install rrdtool, but the error remains.
The docs at https://oss.oetiker.ch/rrdtool/prog/rrdruby.en.html provide two options:
Either:
$: << '/path/to/rrdtool/lib/ruby/1.8/i386-linux'
require "RRD"
In my /opt/homebrew/Cellar/rrdtool/1.8.0/lib directory there's no mention of ruby, which is because of the --disable-ruby-site-install flag in the formula, because when I skip that flag I do actually get something: /opt/homebrew/Cellar/rrdtool/1.8.0/lib/ruby/2.6.0/universal-darwin21. However replacing the path/to string with this path still gives the error.
Or:
If you use the --ruby-site-install configure option you can drop the $: line since the RRDtool module will be found automatically.
Which is a little confusing (and probably outdated) because here it seems that ruby site install is disabled by default and you have to enable it proactively, whereas in the formula it's actually actively disabled.
Either way: both options didn't do the trick for me and if there's a solution without homebrew that's also fine.
For good measure: I'm on macOS Monterey
TL;DR
For the most part, I'd say that using a non-standard gem without a Ruby version manager is your main issue. There are instructions on the rrdruby site for installing it, but they don't follow typical conventions, so your mileage will vary.
Some Practical Suggestions
The require keyword is for gems, not binaries. You need to have an rrdtool-related gem installed, available to your Ruby instance (usually through a Bundler Gemfile or gemspec, or via the RUBYOPTS environment variable or your in-process Ruby $LOAD_PATH), and then require the correct name of the gem in your code. For example, using the older rrd-ffi gem:
# use sudo if you're installing it to the system,
# but I would strongly recommend a ruby version
# manager instead
gem install rrd-ffi
# in your Ruby class/module file
require "rrd"
For the gem you seem to be using, you have to compile the gem first to make it usable, and then ensure it's available in your Ruby $LOAD_PATH (or other gem lookup mechanism) before trying to require it. The error message you're seeing is basically telling you that a gem with that name is not available as called within any of the standard lookup locations.
Again, I'd suggest reading the build documentation for your gem, and then seeing if you can install it as part of a Bundler bundle, RVM gemset, or other non-system approach if you can. Otherwise, follow the directions for the rrdruby tool, which is not available as a standard Rubygems.org gem, in order to make it available before trying to require it.
Beware of Outdated or Non-Standard Gems
Most of the RRD gems I found were quite old; most were 7-8 years old or older, so their compatibility with current Rubies is potentially suspect. The gem-builder you're using is newer, but doesn't seem to be designed as a standard gem, so you need to build it and install it in a suitable lookup path before it can be required. Installing gems as system gems is almost always a bad idea, so I'd strongly recommend building it from source and using a ruby version manager rather than following the rrdtool author's atypical suggestions. YMMV.
I am in the early stages of learning Ruby and want to learn how to debug a gem, but am having trouble finding learning resources around this. A simple example would go a long way for me.
Is debugger the preferred debugger? Where do I require it? How do I set breakpoints with it?
Note: I am making an educated guess that the debugging process may be different depending on the gem that needs debugging, so for reference I am particularly interested in debugging certain issues with Compass.
OK, figured this out on my own. Here were the steps I took..
I am running Ruby 1.9.3 (determined by running ruby -v), so after testing ruby-debug and ruby-debug19, I determined these debuggers were no longer maintained, or at least didn't work properly with my install of ruby1.9.3-p125. This lead me to debugger.
The install instructions that worked were:
$ gem install debugger -- --with-ruby-include=PATH_TO_HEADERS
The PATH_TO_HEADERS on my machine, was simply the source location of ruby:
/Users/myusername/.rvm/src/ruby-1.9.3-p125/
Since I was particularly determined to debug the Compass compiler, I did the following:
Cloned the source: $ git clone git://github.com/chriseppstein/compass.git
Checked existing compass version first $ compass -v which was 13.0
Edited VERSION.yml and increased the patch number (to 13.1) so it didn't conflict with my existing install.
Edited the .rb of the file I wanted to debug, which was lib/compass/compiler.rb and added this line at the top: require 'debugger'; debugger
Built the gem: gem build compass.gemspec
Installed the newly compiled gem: sudo gem install compass-0.13.2.058ead2.gem
Compiled an existing compass based project that I was experiencing problems with, and started debugging.
When I was done debugging, I uninstalled the debugging version with sudo gem uninstall compass and chose the number corresponding to Compass 13.2.
Note about step 7: Since debugger has the same debugging commands as ruby-debug/ruby-debug19, I was able to follow existing tutorials around debugging steps..
Such as this RailsCast:
http://railscasts.com/episodes/54-debugging-with-ruby-debug
And this blog (and linked cheat sheet):
http://pivotallabs.com/users/chad/blog/articles/366-ruby-debug-in-30-seconds-we-don-t-need-no-stinkin-gui-
If you have other debugger tutorials, pointers, tips, etc, please post them.
I have a Gem that I found at RubyForge and want to peek inside to see what code it contains. Is it possible to do this without installing the Gem on my system?
Also, if I use RVM on Mac OS X, does that at all change how my gems get installed (assuming I have one gemset)?
gem unpack unpacks the gem without installing it.
Gems on RubyGems usually have a link to the source code (most often on GitHub), in which case you can easily browse the code (I use this A LOT).
The "homepage" link also tends to link to the repository.
If all else fails, go to GitHub and search for the name of the gem (you may need to match up the authors to ensure it's the right repository for the gem).
Edit:
Just noticed that you asked about gems on Rubyforge. In which case my first step would be to check RubyGems. But otherwise you will need to download the gem and peek inside it (it's just a compressed archive so you can open it up in something like 7-zip).
Many gems have their source freely readable. The way that always works is to install it.
If you just want to browse the source; go to the gem on http://rubygems.org find your gem and use the "Source code" link.
In case of RubyForge you can find the links under the SCM link in the menu.
Sometimes I have seen following code.
gem 'factory_girl','= 1.2.3'
require 'factory_girl'
I tried to look at gem doc but could not find answer to the question of what does the first line do in code above?
What you're looking for in the gem docs is about Coding with Rubygems.
The first line basically says "Hey, go get this gem with this version" from the install directory for gems and load it into the environment. This is mainly to help you add version dependencies to your requires instead of just doing require 'factory_girl' by itself.
Edit: To add on to Jörg's point below, I thought that Ryan Tomayko had a pretty good short and sweet article about why doing this is "wrong".
As #theIV already explained, this activates the factory_girl gem, using exactly (because of the = sign) version 1.2.3.
Note, however, that this is very bad practice and should never be done. If you activate gems manually inside your code, it means that people who do not use RubyGems can no longer use your code.
RubyGems is a package manager. Your code should never care about what package manager was used to install it. Some people prefer RubyGems, some dpkg/APT, some RPM/YUM, some RPM/APT, some RPM/URPMI, some RPM/YaST2, Portage, FreeBSD ports, pkgsrc, MacPorts, slashpackage, CoAPP, Conary, Slackware. There's tons of them. Some people like not to use any package manager at all. Or, they use RubyGems just for downloading, but then unpack the gem into their vendor directory.
All of this cannot possibly work, if you use the gem method in your code.
I was wondering if there was a solution to automatically - from my ruby source code - ask Gem to install various librairies my code my require to work?
From what i read on the internet, it seems we are obliged to either use an install script that directly runs "gem install ..." commands or do it manually or some people have posted a ruby script that simply iterate over a list of dependencies and use the system command to install them.
Any other better options?
Thanks for your time.
You could use internal RubyGems commands, but that's a pain and error-prone process, especially for dependencies.
I would setup a Gemfile and use Bundler instead. http://github.com/carlhuda/bundler