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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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The include method is the way to “inject” code from one module into other modules. or classes. It helps you DRY up your code - avoid duplications. For example, if we have many classes that would need the same functionality we don't have to write the same code in all of them.
In simple words, the difference between include and extend is that 'include' is for adding methods only to an instance of a class and 'extend' is for adding methods to the class but not to its instance.
You should use load function mainly for the purpose of loading code from other files that are being dynamically changed so as to get updated code every time. Require reads the file from the file system, parses it, saves to the memory, and runs it in a given place.
Use require when the file is required by the application. Use include when the file is not required and application should continue when file is not found.
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.
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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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