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The use of `class` for things that should be simple free functions

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Re: The use of `class` for things that should be simple free functions

#231

Post by rashkov »

woah wrote: post #229
amw-zero wrote: post #214

Earlier quoted context omitted.

You don’t agree with an idea so it’s silly? Passing around state via variables is no more tedious than the extra syntax for class definitions, constructors, member variable access, extra semantics related to objects, extra keywords related to visibility, etc. You can encapsulate functionality without objects. There is nothing that you can do with an object that you can’t do with a closure, and the closure version wil…

Seems like kind of a meaningless gesture to pass in your own “this” just because you don’t like OOP. If you need a class, why not write it the idiomatic way?

Maybe I'm mis-reading it, but it seems that your comment is just a re-statement of what your parent comment is replying to. It’s like, “Why A” “Because B” “But why A?”

Re: The use of `class` for things that should be simple free functions

#232

Post by ImprobableTruth »

woah wrote: post #229
amw-zero wrote: post #214

Earlier quoted context omitted.

You don’t agree with an idea so it’s silly? Passing around state via variables is no more tedious than the extra syntax for class definitions, constructors, member variable access, extra semantics related to objects, extra keywords related to visibility, etc. You can encapsulate functionality without objects. There is nothing that you can do with an object that you can’t do with a closure, and the closure version wil…

Seems like kind of a meaningless gesture to pass in your own “this” just because you don’t like OOP. If you need a class, why not write it the idiomatic way?

In what way do you 'need' a class? It uses none of the features that a class provides over normal structs.

Re: The use of `class` for things that should be simple free functions

#233

Post by ergothus »

twic wrote: post #42
makapuf wrote: post #3

Also known in python as "if your class has only two methods, one of which is init, it's a function" in the "stop writing classes" https://www.youtube.com/watch?v=o9pEzgHorH0 EDIT: typo, changed link

I have a few little classes that are clients for network services. They have a constructor which sets up an HTTP client or socket or something, and maybe prepares some metadata, and then a method to make a call to the service. I could write these clients as lambdas or nested functions which close over the stuff which init creates. But why? An object makes it much clearer that there is state.

> But why?

This is my key question, and I ask with minimal assumption that either one is better.

What are the criteria we are even using to judge? Clarity that there is state is one. Elsewhere there are arguments about ABI that I fail to have practical knowledge of. There was some discussion of the data structure describing your program that completely lost me. Explicitness is lost when discussing closures.

What makes one better than the other in ways that arent entirely subjective?

Re: The use of `class` for things that should be simple free functions

#234

Post by commandlinefan »

Although he's correct at a high level, I'd say this should be handled more like the advice given to programmers on optimization:

Optimization for beginners: Don't optimize

Optimization for experts: Don't optimize - yet.

What I've observed, over and over (for the past 20 years of Java development) is that beginning programmers don't really see much point in object-oriented design, and default to static functions (Java's equivalent of "free functions"), but they also end up needing some shared state... so they make the shared state static, too (Java's equivalent of a global variable). Every "enterprise" Java project I've worked on since about 2002 has been "designed" this way: almost all the data is public static (e.g. the "singleton" abomination) so you can't run any of it without running all of it.

On the other hand, if developers just defaulted to designing objects even if they don't really get why, they'll end up with a composable, testable system by accident.

Re: The use of `class` for things that should be simple free functions

#235

Post by sgift »

nightski wrote: post #230
woah wrote: post #229

Earlier quoted context omitted.

Seems like kind of a meaningless gesture to pass in your own “this” just because you don’t like OOP. If you need a class, why not write it the idiomatic way?

I didn't down-vote you, but in my opinion it's not meaningless because it makes it inherently more testable. Try testing an opaque class without any accessibility into its state. It is much more difficult. If it takes in the state, performs an operation, and returns a new version of that state (ideally an immutable copy) then it becomes much easier to test and validate. The reason information hiding is/was advocated…

The class will have to provide you with an option to get your answer back after a computation, so that's what you test. I don't see a reason to test how a class computes a result as long as the result is correct.

Re: The use of `class` for things that should be simple free functions

#236

Post by ImprobableTruth »

raducu wrote: post #221
amw-zero wrote: post #48

Earlier quoted context omitted.

None of these situations require an object to do. You can always have a function that takes in an extra ‘state’ argument. You can then do everything you said by passing in the corresponding state values.

But after a couple of arguments, fields inside an object become more appealing -- this is about taste. But even if you have free functions, as they become more complex, you tend to group them together, so at that point you might just slap the "class" keyword somewhere at the beginning of the file and just call it a class.

>But after a couple of arguments, fields inside an object become more appealing -- this is about taste.

I don't understand this. The difference between passing a structure implicitly or explicitly will always be a single argument.

>But even if you have free functions, as they become more complex, you tend to group them together, so at that point you might just slap the "class" keyword somewhere at the beginning of the file and just call it a class.

Sure, but at that point you're not really using any class features. If you're just using classes as modules, why not use modules directly?

Re: The use of `class` for things that should be simple free functions

#237

Post by nightski »

sgift wrote: post #235
nightski wrote: post #230

Earlier quoted context omitted.

I didn't down-vote you, but in my opinion it's not meaningless because it makes it inherently more testable. Try testing an opaque class without any accessibility into its state. It is much more difficult. If it takes in the state, performs an operation, and returns a new version of that state (ideally an immutable copy) then it becomes much easier to test and validate. The reason information hiding is/was advocated…

The class will have to provide you with an option to get your answer back after a computation, so that's what you test. I don't see a reason to test how a class computes a result as long as the result is correct.

Well either you have internal state or you don't. If you don't have internal state (and it just returns the answer), then there is no difference between it and a function.

If it does have internal state, then the answer it returns depends on the value of that internal state which means it's hard to verify that the answer returned is correct since you have to know the internal state of the object.

Re: The use of `class` for things that should be simple free functions

#238

Post by optimiz3 »

amw-zero wrote: post #214
JoeAltmaier wrote: post #198

Earlier quoted context omitted.

Sure, you can build your own object and pass the 'this' pointer around manually. You could use C for everything, and tediously do everything again that objects do for free. But why? There's a lot of object-hating going around. Its silly. Use objects to encapsulate functionality, they are good at that and everybody understands what it means.

You don’t agree with an idea so it’s silly? Passing around state via variables is no more tedious than the extra syntax for class definitions, constructors, member variable access, extra semantics related to objects, extra keywords related to visibility, etc. You can encapsulate functionality without objects. There is nothing that you can do with an object that you can’t do with a closure, and the closure version wil…

> Passing around state via variables is no more tedious

But it is - the programming language is now repeatedly quizzing you on something you've already told it.

Re: The use of `class` for things that should be simple free functions

#239

Post by lmkg »

logicchains wrote: post #192
cataphract wrote: post #51

Earlier quoted context omitted.

But if you're passing a state object around, you might as well use a class, no? Admittedly simplifying a bit, an instance method is a function that implicitly takes "this" as the first argument.

>But if you're passing a state object around, you might as well use a class, no? A lot of your functions aren't going to need access to the whole state, only to some of it. If we're not using a class, we can just make these functions take only the needed arguments, rather than the whole state. This makes them easier to reason about, as we can know from the function signature that it only looks at the params we pass i…

This sounds like exposing internal implementation details. You're pushing some complexity onto the caller, and breaking up the uniformity of the interface. Sometimes the caller will want to manage that complexity for the reasons that you describe, but it's not always good to force the caller to wrangle that complexity.

Design trade-offs, as always. I get why you would do it your way, and it makes sense in some applications. But for some applications the fact that you're hiding which specific bits of state each function depends on, is actually the point of using a class.

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