What is the difference between require relative and require in Ruby

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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

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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

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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  quot    quot  format  for a file in the current directory  e g  require  quot   my file quot  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  quot within quot  the current directory tree as opposed to  quot up quot   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  quot up and down quot  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  quot stable quot  as it always be relative to the file requiring it in the same way

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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

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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

User · Answer

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

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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

[ruby] What is the difference between require_relative and require in Ruby?

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