Classes are handy. We can call them and invoke them any time. Is this good?
Problems
Coupling
Extensibility
Hard to mock
Solutions
Use interfaces or traits (if available).
Use Dependency Injection.
Favor Loose Coupling.
Sample Code
Wrong
Right
Detection
We can use almost any linter to find references to classes. We should not abuse since many uses might be false positives.
Tags
- Coupling
Conclusion
Dependencies to Interfaces make a system less coupled and thus more extensible and testable.
Interfaces change less often than concrete implementations.
Some objects implement many interfaces, declaring which part depends on which interface makes the coupling more granular and the object more cohesive.
Relations
More info
Credits
Photo by Marco Bianchetti on Unsplash
When your code depends on an interface, that dependency is usually very minor and unobtrusive. Your code doesn’t have to change unless the interface changes, and interfaces typically change far less often than the code behind them. When you have an interface, you can edit classes that implement that interface or add new classes that implement the interface, all without impacting code that uses the interface.
For this reason, it is better to depend on interfaces or abstract classes than it is to depend on concrete classes. When you depend on less volatile things, you minimize the chance that particular changes will trigger massive recompilation.
Michael Feathers
Top comments (5)
I am confused. The solution said that favor loose coupling and the conclusion favor dependency on to the interface. But in the wrong example,
MyDomainclass depends on interface and in the right example it depends on class.Maybe it is swapped?
thank you very much for pointing it out
last minute change. :)
Of course coupled.java was the wrong one!
Hi. I don't know this is an issue with your embedding or just a limitation of the platforms, but when I look at 3 different posts of yours for the first time, then initially the same file is used. On reloading immediately then it is fixed.
Perhaps its because of how multiple files exist in one gist. But doesn't explain buggy gist behavior.
First
Second
Hi.
There is a bug with dev.to app version that messes up gists.
This is not happening on the website
Can you check this out?
It does sound like a bug. I don't think I've seen gists much before here.
I am using mobile web.
Strangely after the first 3 post problems, on the 4th post I clicked, it worked right first time around.