There are lots of “rules” we must follow in object-oriented software development and the article The Genius of the Law of Demeter by Javadevguy summarizes how they are useful. From what I put together, it seems like the Law of Demeter took abstract concepts and basically put them into a universal set of rules for Object-Oriented code.
I thought that the law of demeter must be a big deal if someone decided to sit down and write a lengthy blog post about it. This content ended up being interesting as it tried to convince readers why they should obey this “law.” The Law of Demeter basically paves the way for what users can do to a given method. It is kind of like considering the restrictions or possibilities based on the method. One of the takeaways I got from this is how there is a lot of focus on communication between two objects.
The rules listed in the article are as follows–noting that it says “For all classes C, and for all methods M attached to C, all objects to which M sends a message must be”:
this in Java)
- M’s argument objects
- Instance variable objects of C
- Objects created by M, or by functions or methods which M calls
- Objects in global variables (
static fields in Java)
Another useful takeaway I got from this article came from observing the code examples Javadevguy included; how Rule #1 covers that any method can be called on the current object. I also noted when there would be an instance where the law would prohibit something is not “sending a message” to any already existing object that is held in instance variables of other classes.
This will affect the way I continue to do work as an Object-Oriented developer. I mean, in life when you learn there is a more useful or structured way to help you achieve more effective results, you would want to try or follow it, right? For my future use, I will acknowledge (like other blogs and articles) that the Law of Demeter is less of a law and only a suggestion or a guideline.
Overall, I would say that the content has helped further solidified my understanding of some Object-Oriented coding concepts. I agree with the content as it is trying to help people become better developers or better understand the Law of Demeter in general.
When coding, users always have to be conscious about the way their code may be implemented or used in the future by different services leading to potential misuse. After reading Code Health: Make Interfaces Hard to Misuse by Marek Kiszkis, it made me think about how important communication between testing code is.
I found this content useful because Kiszkis featured some examples that can show how an interface could be misused easily. The examples included:
- Requiring callers to call an initialization function
- Requiring callers to perform custom cleanup
- Allowing code paths that create objects without required parameters
- Allowing parameters for which only some values are valid, especially if it is possible to use a more appropriate type
It is also good to remember that at the end of the day, code should be defensive but not too defensive to the point that complexity is increased and performance overall is reduced. Kiszkis says “it is not always practical to have a foolproof interface” because there will be situations where some requirements are things that cannot be expressed in an interface.
After seeing so much content based on being careful about what you code it is surprising how this article says it is not necessary to plan too hard. I kind of understand why Kiszkis would say this but personally, I kind of disagree with this. The reason why I disagree is because if someone does happen to end up with more time to work on something than expected and they know it will make something more efficient, then why not go for it?
Overall, I appreciated what was shared in this article in terms of encouraging users to try and see issues that can arise with their code when it comes to interfaces. The main takeaway for me is that if something is brought up, or triggered by undefined behavior, a user should try and make it impossible for this to happen. A way of doing so is by adding things where necessary, like certain slots in his example. It does not have to be too specific but detailed enough so that it covers different aspects, similar to how we try to prepare for everything when it comes to equivalence class testing.