| description | last_modified |
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What inversion of control means and why it's useful when building applications |
2020-12-31 13:17:37 UTC |
- Separate code defining how something is done from code defining when it is done
- Ensure that both of these parts know as little as possible about each other
Benefits:
- Decoupling between "how" and "when" parts
- The less they need to know about each other, the easier it is to replace/adjust one without breaking the other
- More focused classes/modules
- Events
- Separate code handling events ("how" part) from code triggering events ("when part")
- Dependency injection
- Pass dependencies of a class/function/module as constructor arguments, method parameters, ...
- "How" is defined inside the dependencies that are injected + in the code that determines which specific implementation will be injected (as opposed to the class/function/module instantiating its own dependencies)
- Second part is very useful for reusability and also makes it easy to pass in specific implementations for running automated tests
- "When" is defined by the code of the class/function/module that uses the dependencies
- The Template method pattern
- Separate implementation of template method ("how" part) from logic for calling the template method ("when" part)
- The Strategy pattern
- Strategy itself defines the "how" part, code calling strategy defines the "when" part
- Good use case for dependency injection