What is the difference between include and require in Ruby

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My question is similar to  What is the difference between include and extend in Ruby     What s the difference between require and include in Ruby   If I just want to use the methods from a module in my class  should I require it or include it

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From the Metaprogramming Ruby book        The require   method is quite similar to load    but it   s meant for   a different purpose  You use load   to execute code  and you use   require   to import libraries

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If you re using a module  that means you re bringing all the methods into your class      If you extend a class with a module  that means you re  bringing in  the module s methods as class methods     If you include a class with a  module  that means you re  bringing in  the module s methods as instance methods   EX    module A    def say      puts  this is module A     end  end   class B    include A  end   class C    extend A  end   B say    undefined method  say  for B Class  B new say    this is module A  C say    this is module A  C new say    undefined method  say  for C Class

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Include     When you include a module into your class  it   s as if you took the   code defined within the module and inserted it within the class  where   you    include    it  It allows the    mixin    behavior  It   s used to DRY up   your code to avoid duplication  for instance  if there were multiple   classes that would need the same code within the module    module Log    def class type      This class is of type    self class     end end  class TestClass    include Log           end  tc   TestClass new class type   - gt  success tc   TestClass class type   - gt  error   Require     The require method allows you to load a library and prevents it from   being loaded more than once  The require method will return    false    if   you try to load the same library after the first time  The require   method only needs to be used if library you are loading is defined in   a separate file  which is usually the case    So it keeps track of whether that library was already loaded or not  You also don   t need to specify the     rb    extension of the library file name  Here   s an example of how to use require  Place the require method at the very top of your     rb    file   Load     The load method is almost like the require method except it doesn   t   keep track of whether or not that library has been loaded  So it   s   possible to load a library multiple times and also when using the load   method you must specify the     rb    extension of the library file name    Extend     When using the extend method instead of include  you are adding the   module   s methods as class methods instead of as instance methods    module Log    def class type      This class is of type    self class     end end  class TestClass    extend Log           end  tc   TestClass class type

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From Programming Ruby 1 9     We   ll make a couple of points about the include statement before we go on  First  it has   nothing to do with files  C programmers use a preprocessor directive called  include to   insert the contents of one file into another during compilation  The Ruby include statement   simply makes a reference to a module  If that module is in a separate file  you must use   require  or its less commonly used cousin  load  to drag that file in before using include    Second  a Ruby include does not simply copy the module   s instance methods into the class    Instead  it makes a reference from the class to the included module  If multiple classes   include that module  they   ll all point to the same thing  If you change the definition of a   method within a module  even while your program is running  all classes that include that   module will exhibit the new behavior

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What s the difference between    include  and  require  in Ruby       Answer       The include and require methods do   very different things       The require method does what include   does in most other programming   languages  run another file  It also   tracks what you ve required in the   past and won t require the same file   twice  To run another file without   this added functionality  you can use   the load method       The include method takes all the   methods from another module and   includes them into the current module    This is a language-level thing as   opposed to a file-level thing as with   require  The include method is the   primary way to  extend  classes with   other modules  usually referred to as   mix-ins   For example  if your class   defines the method  each   you can   include the mixin module Enumerable   and it can act as a collection  This   can be confusing as the include verb   is used very differently in other   languages    Source  So if you just want to use a module  rather than extend it or do a mix-in  then you ll want to use require   Oddly enough  Ruby s require is analogous to C s include  while Ruby s include is almost nothing like C s include

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Ruby require is more like  include  in other languages  such as C   It tells Ruby that you want to bring in the contents of another file  Similar mechanisms in other languages are    using  lt namespace gt  directive in C   import  lt package gt  in Java   Ruby include is an object-oriented inheritance mechanism used for mixins    There is a good explanation here       The  simple answer is that require and include are essentially unrelated        require  is similar to the C include  which may cause newbie confusion     One notable difference is that locals inside the required file  evaporate    when the require is done        The Ruby include is nothing like the C include  The include statement  mixes in  a module into a class  It s a limited form   of multiple inheritance  An included module literally bestows an  is-a    relationship on the thing including it    Emphasis added

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require name    It will return bolean true false  The name which is passed as parameter to the require  ruby will try to find the source file with that name in your load path   The require method will return    false    if you try to load the same library after the first time  The require method only needs to be used if library you are loading is defined in a separate file  So it keeps track of whether that library was already loaded or not   include module name   Suppose if you have some methods that you need to have in two different classes  Then you don t have to write them in both the classes  Instead what you can do is  define it in module  And then include this module in other classes  It is provided by Ruby just to ensure DRY principle   It   s used to DRY up your code to avoid duplication

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Below are few basic differences between require and include    Require    Require reads the file from the file system  parses it  saves to the memory and runs it in a given place which means if you will even change anything while the script is running than that change will not reflect  We require file by name  not by module name  It is typically used for libraries and extensions    Include     When you include a module into your class it behaves as if you took the code defined in your module and inserted it in your class  We include module name  not the file name  It is typically used to dry up the code and to remove duplication in the code

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Ruby require is more like  include  in other languages  such as C   It tells Ruby that you want to bring in the contents of another file  Similar mechanisms in other languages are    using  lt namespace gt  directive in C   import  lt package gt  in Java   Ruby include is an object-oriented inheritance mechanism used for mixins    There is a good explanation here       The  simple answer is that require and include are essentially unrelated        require  is similar to the C include  which may cause newbie confusion     One notable difference is that locals inside the required file  evaporate    when the require is done        The Ruby include is nothing like the C include  The include statement  mixes in  a module into a class  It s a limited form   of multiple inheritance  An included module literally bestows an  is-a    relationship on the thing including it    Emphasis added

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Load - inserts a file s contents  Parse file every time the file is being called    Require - inserts a file parsed content  File parsed once and stored in memory    Include - includes the module into the class and can use methods inside the module as class s instance method   Extend - includes the module into the class and can use methods inside the module as class method

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What s the difference between    include  and  require  in Ruby       Answer       The include and require methods do   very different things       The require method does what include   does in most other programming   languages  run another file  It also   tracks what you ve required in the   past and won t require the same file   twice  To run another file without   this added functionality  you can use   the load method       The include method takes all the   methods from another module and   includes them into the current module    This is a language-level thing as   opposed to a file-level thing as with   require  The include method is the   primary way to  extend  classes with   other modules  usually referred to as   mix-ins   For example  if your class   defines the method  each   you can   include the mixin module Enumerable   and it can act as a collection  This   can be confusing as the include verb   is used very differently in other   languages    Source  So if you just want to use a module  rather than extend it or do a mix-in  then you ll want to use require   Oddly enough  Ruby s require is analogous to C s include  while Ruby s include is almost nothing like C s include

User · Answer

From the Metaprogramming Ruby book        The require   method is quite similar to load    but it   s meant for   a different purpose  You use load   to execute code  and you use   require   to import libraries

User · Answer

What s the difference between    include  and  require  in Ruby       Answer       The include and require methods do   very different things       The require method does what include   does in most other programming   languages  run another file  It also   tracks what you ve required in the   past and won t require the same file   twice  To run another file without   this added functionality  you can use   the load method       The include method takes all the   methods from another module and   includes them into the current module    This is a language-level thing as   opposed to a file-level thing as with   require  The include method is the   primary way to  extend  classes with   other modules  usually referred to as   mix-ins   For example  if your class   defines the method  each   you can   include the mixin module Enumerable   and it can act as a collection  This   can be confusing as the include verb   is used very differently in other   languages    Source  So if you just want to use a module  rather than extend it or do a mix-in  then you ll want to use require   Oddly enough  Ruby s require is analogous to C s include  while Ruby s include is almost nothing like C s include

User · Answer

If you re using a module  that means you re bringing all the methods into your class      If you extend a class with a module  that means you re  bringing in  the module s methods as class methods     If you include a class with a  module  that means you re  bringing in  the module s methods as instance methods   EX    module A    def say      puts  this is module A     end  end   class B    include A  end   class C    extend A  end   B say    undefined method  say  for B Class  B new say    this is module A  C say    this is module A  C new say    undefined method  say  for C Class

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Load - inserts a file s contents  Parse file every time the file is being called    Require - inserts a file parsed content  File parsed once and stored in memory    Include - includes the module into the class and can use methods inside the module as class s instance method   Extend - includes the module into the class and can use methods inside the module as class method

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Have you ever tried to require a module  What were the results  Just try   MyModule   Module new require MyModule   see what happens   Modules cannot be required  only included

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Have you ever tried to require a module  What were the results  Just try   MyModule   Module new require MyModule   see what happens   Modules cannot be required  only included

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Include When you Include a module into your class as shown below  it   s as if you took the code defined within the module and inserted it within the class  where you    include    it  It allows the    mixin    behavior  It   s used to DRY up your code to avoid duplication  for instance  if there were multiple classes that would need the same code within the module   Load The load method is almost like the require method except it doesn   t keep track of whether or not that library has been loaded  So it   s possible to load a library multiple times and also when using the load method you must specify the     rb    extension of the library file name   Require The require method allows you to load a library and prevents it from being loaded more than once  The require method will return    false    if you try to load the same library after the first time  The require method only needs to be used if library you are loading is defined in a separate file  which is usually the case   You can prefer this  http   ionrails com 2009 09 19 ruby require-vs-load-vs-include-vs-extend

User · Answer

Ruby require is more like  include  in other languages  such as C   It tells Ruby that you want to bring in the contents of another file  Similar mechanisms in other languages are    using  lt namespace gt  directive in C   import  lt package gt  in Java   Ruby include is an object-oriented inheritance mechanism used for mixins    There is a good explanation here       The  simple answer is that require and include are essentially unrelated        require  is similar to the C include  which may cause newbie confusion     One notable difference is that locals inside the required file  evaporate    when the require is done        The Ruby include is nothing like the C include  The include statement  mixes in  a module into a class  It s a limited form   of multiple inheritance  An included module literally bestows an  is-a    relationship on the thing including it    Emphasis added

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require name    It will return bolean true false  The name which is passed as parameter to the require  ruby will try to find the source file with that name in your load path   The require method will return    false    if you try to load the same library after the first time  The require method only needs to be used if library you are loading is defined in a separate file  So it keeps track of whether that library was already loaded or not   include module name   Suppose if you have some methods that you need to have in two different classes  Then you don t have to write them in both the classes  Instead what you can do is  define it in module  And then include this module in other classes  It is provided by Ruby just to ensure DRY principle   It   s used to DRY up your code to avoid duplication

User · Answer

Ruby require is more like  include  in other languages  such as C   It tells Ruby that you want to bring in the contents of another file  Similar mechanisms in other languages are    using  lt namespace gt  directive in C   import  lt package gt  in Java   Ruby include is an object-oriented inheritance mechanism used for mixins    There is a good explanation here       The  simple answer is that require and include are essentially unrelated        require  is similar to the C include  which may cause newbie confusion     One notable difference is that locals inside the required file  evaporate    when the require is done        The Ruby include is nothing like the C include  The include statement  mixes in  a module into a class  It s a limited form   of multiple inheritance  An included module literally bestows an  is-a    relationship on the thing including it    Emphasis added

User · Answer

Include     When you include a module into your class  it   s as if you took the   code defined within the module and inserted it within the class  where   you    include    it  It allows the    mixin    behavior  It   s used to DRY up   your code to avoid duplication  for instance  if there were multiple   classes that would need the same code within the module    module Log    def class type      This class is of type    self class     end end  class TestClass    include Log           end  tc   TestClass new class type   - gt  success tc   TestClass class type   - gt  error   Require     The require method allows you to load a library and prevents it from   being loaded more than once  The require method will return    false    if   you try to load the same library after the first time  The require   method only needs to be used if library you are loading is defined in   a separate file  which is usually the case    So it keeps track of whether that library was already loaded or not  You also don   t need to specify the     rb    extension of the library file name  Here   s an example of how to use require  Place the require method at the very top of your     rb    file   Load     The load method is almost like the require method except it doesn   t   keep track of whether or not that library has been loaded  So it   s   possible to load a library multiple times and also when using the load   method you must specify the     rb    extension of the library file name    Extend     When using the extend method instead of include  you are adding the   module   s methods as class methods instead of as instance methods    module Log    def class type      This class is of type    self class     end end  class TestClass    extend Log           end  tc   TestClass class type

User · Answer

Include When you Include a module into your class as shown below  it   s as if you took the code defined within the module and inserted it within the class  where you    include    it  It allows the    mixin    behavior  It   s used to DRY up your code to avoid duplication  for instance  if there were multiple classes that would need the same code within the module   Load The load method is almost like the require method except it doesn   t keep track of whether or not that library has been loaded  So it   s possible to load a library multiple times and also when using the load method you must specify the     rb    extension of the library file name   Require The require method allows you to load a library and prevents it from being loaded more than once  The require method will return    false    if you try to load the same library after the first time  The require method only needs to be used if library you are loading is defined in a separate file  which is usually the case   You can prefer this  http   ionrails com 2009 09 19 ruby require-vs-load-vs-include-vs-extend

User · Answer

From Programming Ruby 1 9     We   ll make a couple of points about the include statement before we go on  First  it has   nothing to do with files  C programmers use a preprocessor directive called  include to   insert the contents of one file into another during compilation  The Ruby include statement   simply makes a reference to a module  If that module is in a separate file  you must use   require  or its less commonly used cousin  load  to drag that file in before using include    Second  a Ruby include does not simply copy the module   s instance methods into the class    Instead  it makes a reference from the class to the included module  If multiple classes   include that module  they   ll all point to the same thing  If you change the definition of a   method within a module  even while your program is running  all classes that include that   module will exhibit the new behavior

User · Answer

Below are few basic differences between require and include    Require    Require reads the file from the file system  parses it  saves to the memory and runs it in a given place which means if you will even change anything while the script is running than that change will not reflect  We require file by name  not by module name  It is typically used for libraries and extensions    Include     When you include a module into your class it behaves as if you took the code defined in your module and inserted it in your class  We include module name  not the file name  It is typically used to dry up the code and to remove duplication in the code

User · Answer

What s the difference between    include  and  require  in Ruby       Answer       The include and require methods do   very different things       The require method does what include   does in most other programming   languages  run another file  It also   tracks what you ve required in the   past and won t require the same file   twice  To run another file without   this added functionality  you can use   the load method       The include method takes all the   methods from another module and   includes them into the current module    This is a language-level thing as   opposed to a file-level thing as with   require  The include method is the   primary way to  extend  classes with   other modules  usually referred to as   mix-ins   For example  if your class   defines the method  each   you can   include the mixin module Enumerable   and it can act as a collection  This   can be confusing as the include verb   is used very differently in other   languages    Source  So if you just want to use a module  rather than extend it or do a mix-in  then you ll want to use require   Oddly enough  Ruby s require is analogous to C s include  while Ruby s include is almost nothing like C s include

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

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