Google TechTalks
3 HN recommenders · recommended in 6 months, 2009–2023
38:25 · 438K views · Dec 5, 2008
Misko Hevery's Clean Code Talk shows how to use object-oriented techniques such as polymorphism to remove repeated if and switch statements. The result is code that is easier to test, understand and maintain.
HN commenters recommend it as a thorough treatment of replacing conditionals with polymorphism and why flags and deep ifs can be code smells.
6 comments from Hacker News
It's not so much the existence of the flag, itself, but rather using an if-statement at the deepest-level of the call stack to conditionally modify behavior. This talk gives a great overview of why boolean flags (rather, if-statements) can be a code smell: this video OP's blogpost advocates for data-oriented design (e.g. Entity Component Systems) as a mechanism for avoiding this, whereas the talk I've linked advocates for OOP. Both mechanisms are equally valid (imho) and are inline with widely-adopted industry practices for software architecture.
I completely disagree with the example given in this blog. I don't have time to give a full explaination but I believe the google clean code talks gives a far better arguement than I ever could. On the general principle I agree that overengineering is to be avoided, but I actually think the example shows a clear disregard for Object Orientated principles. this video
Google posted a tech talk about this a while ago: this video which is more comprehensive than the posted article.
I think this is actually a great example of why `if` should be "pushed up." The objective of the code is to perform an particular operation on the walrus, given a condition. The is actually ifs being instead of polymorphism and a type system. Why does the walrus have these two functions, which must be called in different scenarios? Why not have a single function, and two types, and the correct type is passed in? Even given the current structure, we could accomplish this: // There are better ways to accomplish this, depending on the language func frobnicate(walrus) { return walrus.frobnicate(); } func transmogrify(walrus) { return walrus.transmogrify(); } // Somewhere high in the code if condition { processing_function = frobnicate } else { processing_function = transmogrify } // Somewhere else in the code for walrus in walruses { processing_function() } If the decisions are made as early as possible, they do not need to be littered throughout the code. The guts of the code can run without branches, performing the same operations every time, the output only modified through the construction graph. Of course, this is not a new idea: this video It was old 15 years ago.
Misko Hevery did a Google Tech Talk about this some years ago, he also use a very similar example with switching on the birds. this video