MacRuby 0.5 includes a ruby compiler built on LLVM called macrubyc.
Does anyone know if it would be possible to dynamically load gems from compiled code? Or compile the gems and link them in? Is this planned? Or how compiled code will be able to make use of gems in general.
Turns out that as of MacRuby 0.6, something like this will compile
require 'rubygems'
require 'sequel'
DB = Sequel.mysql(...)
But fail at run time trying to load mysql leading me to think that it loads the gems at run time.
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Which is a little confusing (and probably outdated) because here it seems that ruby site install is disabled by default and you have to enable it proactively, whereas in the formula it's actually actively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 just started using MacRuby for a simple Mac Application, and I now have a problem.
For my project I use the rmagick gem.
I installed it as described with the command
sudo macgem install rmagick
Everything worked well, but the problem is that if I try to load it in my AppDelegate.rb file with require 'rmagick'. I get an error saying that there is no such file to load.
This is strange, because I noticed that if I first build the project normally and then build the deployment target, I'm able to execute the application without any problems.
It would be really cool if there would be a way to use the gem in the development target, because otherwise I need 30 seconds after each change I made which in total is really much xD
Yeah RMagick can be a tricky one:
require 'rubygems'
require 'RMagick'
is the answer. Also macruby apparently still requires the require 'rubygems'. But beware, the module you actually will be using is called Magick.
A short example:
require 'rubygems'
require 'RMagick'
image = Magick::Image.new "path/to/image.png"
Here you will find the RMagick-documentation.
I'm trying to create a gem with Bundler, following this guide: http://rakeroutes.com/blog/lets-write-a-gem-part-one/. In it, it says:
I incorrectly thought after taking my first look through the gemspec
that I would need to add more require statements as I developed my
gem. That isn’t the case: the files just need to be in git.
I am trying to clean up some of my old gems to use this convention, but when I install my gem, the classes from the other files are not available. I have a couple directories nested under my /lib dir, but I wouldnt think that would be an issue. Is there anything simple to overlook that would prevent my other files from being required? Any help would be appreciated.
In the link, when he says he doesn't need to add a lot of "require" statements, he must mean adding files to the s.files, s.executables, and s.test_files arrays--these determine what files get packaged up into the gem and what files get ignored. As you can see from the gem spec, whatever's tracked by git in certain directories is going to be included in the packaged gem.
Ruby's require is a different story. Standard require rules still apply.
Ruby's gem system works by adding a bunch of different places for Ruby to look for "foo.rb" when you run require "foo". If "lib" is your only require path for your gem, when you require "my_gem" Ruby is only going to run the code in lib/my_gem.rb. If lib/my_gem.rb doesn't require any other files in your gem, then Ruby hasn't seen them and so you'll get undefined constant errors when you try to use the classes from those files.
For examples, you might take a look at two simple gems I've written; both were started with bundle gem: HashToHiddenFields and SimpleStats. In both gems, main Ruby file in lib/ requires everything that needs to be loaded for the gem to work correctly. For example, hash_to_hidden_fields.rb requires action_view/helpers/hash_to_hidden_fields so that the ActionView::Helpers::HashToHiddenFields constant+module exists so we can include it into ActionView::Base.
Hope that answers the question. I know Ruby requiring was pretty fuzzy to me for a while.
Been running into a problem ever since I started using rvm to manage my ruby installation. Whenever I want to require another class I've written, such as require 'filename', I get a require - no such file to load error when I try to run my script. If I switch back to my system ruby using rvm use system it works again, but I'm 1.8.2 as my system ruby and some features I want to use in my code are only available in 1.9.*, which I can access through rvm. How do I fix this problem?
I'm not sure this is a problem with RVM, but a problem with Ruby 1.9 not including '.' in the current path. For instance, if you are trying to require a library at './lib/file.rb', you can't do
require "lib/file"
You have to do this:
require "./lib/file"
Have you tried that syntax for your require?
I think you want to use require_relative
http://extensions.rubyforge.org/rdoc/classes/Kernel.html
I am editing a gem in which there are the usual require commands, pointing at the loaded gem (the gem I'm talking about is called nirvana, and the files in it contain require 'nirvana', require 'nirvana/shell' and so on).
When I use the bin-file of the application (/mypath/nirvana/bin/nirvana), I want the require 'nirvana' command written inside it to point to the files in the local fork of that gem (the ones I am editing), and I want not to load the original nirvana gem, that is installed with the classic gem install.
I don't want to substitute all the require 'nirvana' commands with
require File.dirname(File.expand_path(__FILE__)) + '/../lib/nirvana.rb'
... this would resolve my problem, but it's ugly! Is there a way to do not load nirvana gem, and to make require 'nirvana' load my libraries (maybe adding them in the $LOAD_PATH...) ?
You might be running into the require vs. require_relative conundrum in 1.9+.
require is good for loading a gem that is loaded via the normal gems paths, i.e., installed into Ruby's space.
require_relative is good for loading relative to a particular file, for instance, if you're loading a module you wrote and its in the same or a sub-directory or relative directory of yours.
`require_relative 'some/sub/dir/to/file'`
You should only be 'requiring' nirvana.rb once, if you're doing so from your gems binary executable. So this line only needs to appear once. It's quite common to see it appear in these files.
Do note your example can be better written as
require File.expand_path('../lib/nirvana.rb', __FILE__)
As File::expand_path takes an optional second argument (a directory String).
A lot of authors will also shift the lib directory into the $LOAD_PATH before executing the binary so the local files are loaded before attempting to load any installed gems.
If you're using rvm, have a look at gemsets. You can create a gemset that doesn't have the nirvana gem installed, then when you require 'nirvana' you'll only get your local libraries required, as there isn't a nirvana gem to include.
(I'm assuming you're using ruby 1.9, as if you're using 1.8 you could just omit require 'rubygems'.)