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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

#221

Post by raducu »

amw-zero wrote: post #48
dataflow wrote: post #18

Counter-point: while in many situations this isn't the right approach, it's worth recognizing when this is the right approach, because they can look awfully similar. An example of this is graph searching, e.g. BFS or Dijkstra's algorithm. The typical implementation is a function. But if you make Dijkstra a class, with (say) a function to iterate through nodes, it lets you do several things that would be difficult wit…

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.

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

#222

Post by fnord123 »

jcelerier wrote: post #200
mrep wrote: post #178

Earlier quoted context omitted.

> Very few professional developers code in vim or notepad Notepad++ and vim are the 3rd and 5th most popular development environment according to stack overflows 2019 report [0] and I and many others I know use Vim at least. > IDE knows types of things, type `myobj.` and you'll get a suggestion list with methods of that class callable from the current context. I've never used notepad but Vim absolutely supports omni…

> Notepad++ and vim are the 3rd and 5th most popular development environment according to stack overflows 2019 report [0] and I and many others I know use Vim at least. in C++ the ratio of ppl I know using an IDE with semantic code completion ability (that is, not rtags but actually using e.g. libclang or something that does understand C++ to some extent for IDE completion) vs "glorified text editors" must be 95/100…

Vim and VS Code have access to semantic code completion through the language server protocol.

But your assertion is weird. Either you work on Windows where everyone is on Visual Studio, or you have 95/100 people around you using CLion, XCode, and Qt Creator, two of which don't even have an entry on GP's survey link. One of which is probably only used to sign apps for ios. Could you give more info?

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

#223

Post by fastball »

im3w1l wrote: post #216
fastball wrote: post #210

Earlier quoted context omitted.

At the same time, if your function has an expensive initialization step that only needs to be called once (and doesn't change between calls), then the pattern of using `__init__()` + `__call__()` can be very nice.

I would consider this pattern: def x(): expensive precompute def y(): cheap stuff return y It's a matter of taste I guess.

For comparisons sake:

  class Thing:
    def __init__(self, arg):
      # expensive precompute
      self.result = ...
    
    def __call__(self, arg):
      # cheap stuff that uses self.result for something
      ...
And then usage is:

  f = Foo("some val")
  bar = f("another val")
So yeah, both definitely do the same job. And your pattern is probably faster. But I generally like using Python's dunder methods as I think they allow for more consistent/recognizable code patterns.

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

#224

Post by yawboakye »

JoeAltmaier wrote: post #198
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.

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 lost me at “there’s a lot of object-hating going around.” Conversely there’s a return to being mindful of how we use the computer’s resources. Lately I’ve been reading about Ruby internals, and rather than be impressed I’m terrified by how staples such as classes are implemented.

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

#225

Post by asveikau »

jcelerier wrote: post #137
fnord123 wrote: post #113

Earlier quoted context omitted.

Let's use C and C++ as an example. What does the code look like? myobj.cool_func(1,2,3); // C++ cool_func(myobj, 1, 2, 3); // C Is this better? If you use a vanilla C++ style class then the class definition is in the header. All changes to the class require a recompilation and break the ABI of the class. This means you basically cannot release patch versions of your library because consumers cannot link against it if…

> If you use a vanilla C++ style class then the class definition is in the header. All changes to the class require a recompilation and break the ABI of the class. definitely not all, only things that change the layout. adding a non-virtual method does not break ABI at all for instance. > Contrast with C where you would forward declare a struct in the header and pass that around while the definition is hidden in a .c…

> Does this have a point in 2020 ? Good modern practice (c.f. Rust, etc) is to ship LTO'ed mostly-static binaries.

It sure sounds to me like modern practice as you've defined it is that when a component has a security vulnerability you're not going to patch it. It's going to be statically linked and running in a container image maybe created by somebody else and you'll have no idea it's there.

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

#226

Post by default-kramer »

Whether or not a class can be reduced to an int is something to consider, but should not automatically proscribe the use of a class. What is way more important is to carefully consider the API that you provide to calling code. Once other code starts depending on your decision, it becomes harder (or even impossible) to change. So you might decide to use a class for this reason, even if it can be reduced to an int.

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

#227

Post by gpderetta »

jcelerier wrote: post #200
mrep wrote: post #178

Earlier quoted context omitted.

> Very few professional developers code in vim or notepad Notepad++ and vim are the 3rd and 5th most popular development environment according to stack overflows 2019 report [0] and I and many others I know use Vim at least. > IDE knows types of things, type `myobj.` and you'll get a suggestion list with methods of that class callable from the current context. I've never used notepad but Vim absolutely supports omni…

> Notepad++ and vim are the 3rd and 5th most popular development environment according to stack overflows 2019 report [0] and I and many others I know use Vim at least. in C++ the ratio of ppl I know using an IDE with semantic code completion ability (that is, not rtags but actually using e.g. libclang or something that does understand C++ to some extent for IDE completion) vs "glorified text editors" must be 95/100…

I use emacs with clangd on a fairly large (~2M lines of code), but between clangd getting stuck, crashing or being too slow, I don't really get much benefits from it. When it works is great though.

TBH, in my limited experience, I have never seen code completion working well on large C++ code bases. I remember years ago VS literally becoming unresponsive when intellisense was enabled.

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

#228

Post by mcv »

cerberusss wrote: post #72
hamandcheese wrote: post #68

Is there any real harm though? Free functions pollute the global namespace, which is something I tend to avoid (at least in Ruby where everything shares the same namespace).

What's the difference between polluting the global namespace with a class name, or with a function name? I get it, I also experience some reticience when adding free/bare functions in Swift. But maybe it's because of 15 years of OOP programming.

Maybe the problem here is the global namespace. I really like modern javascript where you have to explicitly import everything.

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

#229

Post by woah »

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…

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?

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

#230

Post by nightski »

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?

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 was for reduced coupling. But in reality I find that this coupling becomes implicit which is arguably worse. But this is just my opinion.

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