I have a class defined in one file , say testAAA.rb
in the directory, I have another file
I found the following are all wrong
require "testAAA"
require "testAAA.rb"
load "testAAA"
it seems that I can only use load "testAAA.rb"
I think using load "testAAA.rb" looks ugly, how can I make it correct to use "require testAAA" in this case
require searches for files in the load path (which is in the $LOAD_PATH global, aliased as $:), and the current directory isn’t on the load path by default (it used to be in earlier versions of Ruby).
The are a few ways to require the file you want, the simplest here is probably to use require_relative:
require_relative "testAAA"
This is pretty much the same as something like this, which explicitly constructs an absolute path to the required file based on the first file:
require File.expand_path("../testAAA", __FILE__)
You could also explicitly load the file relative to the current working directory using ./:
require "./testAAA"
Note this isn’t the same as requiring the file relative to the first file, the working directory may not be the same directory as where the first file is. They will happen to be the same if you start your program in the same directory.
You could also add the directory in question to the load path. You probably don’t want to be doing this for simple scripts, it is more useful when creating larger apps:
$LOAD_PATH.unshift File.dirname(__FILE__) # or whatever directory you want to add
require 'foo'
If you are using the load method you must include the extension .rb. If you are using the require statement, you leave out the extension. Examples are below;
load 'yourfilehere.rb'
require 'yourfilehere'
Related
I want to require a file called config.rb in a different ruby file called basics.rb. I'm using Sinatra as my web framework. I'm sure there's a way to do this, I just can't find anything in the docs.
Hopefully it would look something like
post '/' do
require 'config.rb'
// logic
end
If config.rb is in your load path, you can require it at the top of your basics.rb file with require 'config'. If it is not in your load path, you'll need something like require '/path/to/your/config'.
The code you've posted will require the file. But only when someone POSTs to '/'.
Also, it's normal to omit the .rb extension when requiring ruby files. But you can include it if you like.
You can view your load path by inspecting the global variable $LOAD_PATH. From the command line ruby -e 'puts $LOAD_PATH' will print it for your version of ruby. You can also add directories to your load path.
I have a RSpec test for a class in /lib/classes which needs access to a zip file (no upload). The file is stored in /spec/fixtures/files/test.zip. How do I input the correct path so it's environment agnostic, i.e. without absolute path?
Rails.root will give you the app root, so
Rails.root.join "spec/fixtures/files/test.zip"
will give you the absolute path of your file, agnostic of the location of the app on your hard drive.
I've tackled this issue recently and here's what I came up with:
Define a constant in your spec_helper.rb (or equivalent) pointing to RSpec root:
RSPEC_ROOT = File.dirname __FILE__
Use this variable in your *_spec.rb (or equivalent) test files:
require 'spec_helper'
File.open("#{RSPEC_ROOT}/resources/example_data.json")
Why this solution?
It doesn't make use of the location of the test file which may be
subject to change (spec_helper is likely not)
It doesn't require any additions to test files other than the already existing
require 'spec_helper'
It doesn't depend on Rails (unlike Rails.root)
Here's a Gist: https://gist.github.com/thisismydesign/9dc142f89b82a07e413a45a5d2983b07
As far as I know (from looking every month or two) there is no better way that building something in spec_helper that uses the __FILE__ value to grab the path to a know bit of content, then build your own helpers on top of that.
You can obviously use a path relative to __FILE__ in the individual *_spec.rb file as well.
What is the difference between require_relative and require in Ruby?
Just look at the docs:
require_relative complements the builtin method require by allowing you to load a file that is relative to the file containing the require_relative statement.
For example, if you have unit test classes in the "test" directory, and data for them under the test "test/data" directory, then you might use a line like this in a test case:
require_relative "data/customer_data_1"
require_relative is a convenient subset of require
require_relative('path')
equals:
require(File.expand_path('path', File.dirname(__FILE__)))
if __FILE__ is defined, or it raises LoadError otherwise.
This implies that:
require_relative 'a' and require_relative './a' require relative to the current file (__FILE__).
This is what you want to use when requiring inside your library, since you don't want the result to depend on the current directory of the caller.
eval('require_relative("a.rb")') raises LoadError because __FILE__ is not defined inside eval.
This is why you can't use require_relative in RSpec tests, which get evaled.
The following operations are only possible with require:
require './a.rb' requires relative to the current directory
require 'a.rb' uses the search path ($LOAD_PATH) to require. It does not find files relative to current directory or path.
This is not possible with require_relative because the docs say that path search only happens when "the filename does not resolve to an absolute path" (i.e. starts with / or ./ or ../), which is always the case for File.expand_path.
The following operation is possible with both, but you will want to use require as it is shorter and more efficient:
require '/a.rb' and require_relative '/a.rb' both require the absolute path.
Reading the source
When the docs are not clear, I recommend that you take a look at the sources (toggle source in the docs). In some cases, it helps to understand what is going on.
require:
VALUE rb_f_require(VALUE obj, VALUE fname) {
return rb_require_safe(fname, rb_safe_level());
}
require_relative:
VALUE rb_f_require_relative(VALUE obj, VALUE fname) {
VALUE base = rb_current_realfilepath();
if (NIL_P(base)) {
rb_loaderror("cannot infer basepath");
}
base = rb_file_dirname(base);
return rb_require_safe(rb_file_absolute_path(fname, base), rb_safe_level());
}
This allows us to conclude that
require_relative('path')
is the same as:
require(File.expand_path('path', File.dirname(__FILE__)))
because:
rb_file_absolute_path =~ File.expand_path
rb_file_dirname1 =~ File.dirname
rb_current_realfilepath =~ __FILE__
Summary
Use require for installed gems
Use require_relative for local files
require uses your $LOAD_PATH to find the files.
require_relative uses the current location of the file using the statement
require
Require relies on you having installed (e.g. gem install [package]) a package somewhere on your system for that functionality.
When using require you can use the "./" format for a file in the current directory, e.g. require "./my_file" but that is not a common or recommended practice and you should use require_relative instead.
require_relative
This simply means include the file 'relative to the location of the file with the require_relative statement'. I generally recommend that files should be "within" the current directory tree as opposed to "up", e.g. don't use
require_relative '../../../filename'
(up 3 directory levels) within the file system because that tends to create unnecessary and brittle dependencies. However in some cases if you are already 'deep' within a directory tree then "up and down" another directory tree branch may be necessary. More simply perhaps, don't use require_relative for files outside of this repository (assuming you are using git which is largely a de-facto standard at this point, late 2018).
Note that require_relative uses the current directory of the file with the require_relative statement (so not necessarily your current directory that you are using the command from). This keeps the require_relative path "stable" as it always be relative to the file requiring it in the same way.
From Ruby API:
require_relative complements the
builtin method require by allowing you
to load a file that is relative to the
file containing the require_relative
statement.
When you use require to load a file,
you are usually accessing
functionality that has been properly
installed, and made accessible, in
your system. require does not offer a
good solution for loading files within
the project’s code. This may be useful
during a development phase, for
accessing test data, or even for
accessing files that are "locked" away
inside a project, not intended for
outside use.
For example, if you have unit test
classes in the "test" directory, and
data for them under the test
"test/data" directory, then you might
use a line like this in a test case:
require_relative "data/customer_data_1"
Since neither
"test" nor "test/data" are likely to
be in Ruby’s library path (and for
good reason), a normal require won’t
find them. require_relative is a good
solution for this particular problem.
You may include or omit the extension
(.rb or .so) of the file you are
loading.
path must respond to to_str.
You can find the documentation at http://extensions.rubyforge.org/rdoc/classes/Kernel.html
The top answers are correct, but deeply technical. For those newer to Ruby:
require_relative will most likely be used to bring in code from another file that you wrote.
for example, what if you have data in ~/my-project/data.rb and you want to include that in ~/my-project/solution.rb? in solution.rb you would add require_relative 'data'.
it is important to note these files do not need to be in the same directory. require_relative '../../folder1/folder2/data' is also valid.
require will most likely be used to bring in code from a library someone else wrote.
for example, what if you want to use one of the helper functions provided in the active_support library? you'll need to install the gem with gem install activesupport and then in the file require 'active_support'.
require 'active_support/all'
"FooBar".underscore
Said differently--
require_relative requires a file specifically pointed to relative to the file that calls it.
require requires a file included in the $LOAD_PATH.
I just saw the RSpec's code has some comment on require_relative being O(1) constant and require being O(N) linear. So probably the difference is that require_relative is the preferred one than require.
I want to add that when using Windows you can use require './1.rb' if the script is run local or from a mapped network drive but when run from an UNC \\servername\sharename\folder path you need to use require_relative './1.rb'.
I don't mingle in the discussion which to use for other reasons.
absolute path
require './app/example_file.rb'
shortened name
require_relative 'example_file'
I have a Ruby code with different classes in a few files. In one file, I start the execution. This file requires my other files.
Is this a good way to start a ruby code?
When I run the code from a symbolic link, for example DIR2/MyRubyCode is a link to the main file DIR1/MyRubyCode.rb, then my requires will fail. I solved the problem by adding the path DIR1 to $LOAD_PATH before the require, but I think there would be much better ways to do it. Do you have any suggestions about that?
If you're using Ruby 1.9 or greater, user require_relative for your dependencies.
require_relative 'foo_class'
require_relative 'bar_module'
If you want to check if a Ruby file is being 'require'ed or executed with 'ruby MyRubyCode.rb', check the __FILE__ constant.
# If the first argument to `ruby` is this file.
if $0 == __FILE__
# Execute some stuff.
end
As far as the require/$LOAD_PATH issue, you could always use the relative path in the require statement. For example:
# MyRubyCode.rb
require "#{File.dirname(__FILE__)}/foo_class"
require "#{File.dirname(__FILE__)}/bar_module"
Which would include the foo_class.rb and bar_module.rb files in the same directory as MyRubyCode.rb.
I know this is an old question, but there is an updated answer to it, and I wanted to post it:
Starting in a more recent version of Ruby (I'm not sure when), you can require files in the same directory by using the following:
require './foo_class'
require './bar_module'
and it'll load files called foo_class.rb and bar_module.rb in the same directory.
For checking if your file is being required or ran normally, check the other answer.
I have a folder full of ruby files, and when I try and require one file in another that is in the same directory using require 'file' I get a LoadError but when I use require './file' everything works fine. Can somebody explain to me why this happens and if there is any way I can require a file without adding a ./ onto the file?
(Picture of directory):
If you want to require a file not from the system $LOAD_PATH but rather relative to the directory of the file you are requireing from, you should use require_relative. (Which, as you can see, isn't exactly extensively documented.)
You don't have current directory in your loadpath.
Check the contents of the $LOAD_PATH variable
Though it is very old post I think some extra information will be very useful to beginner.
The best way to think of require is in relation to the UNIX $PATH variable. Just by way of a refresher, the $PATH variable in UNIX is a list of directories where executables can be found. So when you type the name of a program on any UNIX terminal, your computer is looking through the executable files in the directories specified in your $PATH variable. require does something very similar. When, for example, you write require 'set' at the top of your Ruby file, you are telling Ruby to look through a bunch of directories for a library called set.rb (Ruby's set library).
So where does Ruby look for set.rb? Well, once again, Ruby has something very similar to UNIX's $PATH variable. It is the global variable $LOAD_PATH also sometimes known by it's ugly and undescriptive alias $: (which I don't suggest using by the way--short though it may be). It is an array of directory names where Ruby looks when it comes across a require.
There is nice informative post here where you can get more information about require, load and require_relative