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zengid · 2 months ago
Heard about this watching Casey Muratori's "The Big OOPs" talk [0]. Thought it couldn't be _that_ Hickey, but turns out it was!

[0] https://youtu.be/wo84LFzx5nI?si=SBv1UqgtKJ1BH3Cw&t=5159

drnick1 · 2 months ago
C++ was so much cleaner in the 90s, when it was still essentially "C with classes," which is how I like to use the language. Modern standards have turned it into an ugly mess.
drob518 · 2 months ago
Amen. The syntax just kept getting more and more complicated. I gave up in the late 1990s. Ironically for this post, I now prefer to write everything in Clojure. It seems like my own journey has paralleled Rich’s journey. Maybe that’s why I appreciate so many of the design choices in Clojure. It’s not perfect, but it’s really, really good.
lbalazscs · 2 months ago
A sentence from the article: "Given the extreme undesirability of any new language features I'd hardly propose bound-pointers now."

It shows that C++ was considered too complex already in the 90s.

codr7 · 2 months ago
And then they introduced coke at committee meetings, the crazy shit they've been coming up with lately shows absolutely zero understanding of the complexity issue.
pton_xd · 2 months ago
I also use C++ as "C with classes," however I will concede that many of the modern C++ additions, particularly around templating, are extremely convenient. If you haven't had a chance to use requires, concepts, "using" aliases, etc I'd recommend giving them a try. I don't reach for those tools often, but when I do, they're way nicer than whatever this article is demonstrating from 1994! Oh yeah, also lambdas, those are awesome.
asveikau · 2 months ago
I dunno, I skimmed the article's 31 year old code examples and immediately thought they would be shorter and simpler in c++11 or later.

But it's important to see the 1994 (and 1998) view of the world to understand how modern c++ features work. Because they start from that worldview and start adding convenient stuff. If you don't understand how c++ used to work, you may be confused with why c++ lambdas look so weird.

MomsAVoxell · 2 months ago
>ugly mess

That may be the case, but there are plenty of examples of elegant implementations.

JUCE, for instance:

    #include <juce_core/juce_core.h>

    class MyComponent {
    public:
        void doAsyncOperation(std::function<void(int)> callback) {
            // Simulate async work
            juce::MessageManager::callAsync([callback]() {
                callback(42); // Call the functor with result
            });
        }
    };

    // Usage
    MyComponent comp;
    comp.doAsyncOperation([](int result) {
        juce::Logger::writeToLog("Callback received with: " + juce::String(result));
    });
.. I think that's kind of clean and readable, but ymmv, I guess?

tialaramex · 2 months ago
Well, that definitely doesn't look "clean and readable" to me for whatever that's worth.
spacechild1 · 2 months ago
No member function templates, no variadic templates, no std::function, no lambdas, etc. That's certainly not the kind of C++ I would want to write...
adzm · 2 months ago
You can just use the parts you want though; that's part of its appeal.
eschaton · 2 months ago
This is a thing C++ advocates say that tells me they’ve never really tried to do it and share that codebase with others or integrate with other codebases.

You generally don’t get to pick what parts other people want to use, which means that in the end you still have to deal with the entirety of the language.

dang · 2 months ago
Related. Others?

Callbacks in C++ using template functors (1994) - https://news.ycombinator.com/item?id=18650902 - Dec 2018 (50 comments)

Callbacks in C++ using template functors – Rich Hickey (1994) - https://news.ycombinator.com/item?id=12401400 - Aug 2016 (1 comment)

Callbacks in C++ using template functors (1994) - https://news.ycombinator.com/item?id=10410864 - Oct 2015 (2 comments)

zengid · 2 months ago
not sure why the title was renamed, but i thought this was interesting primarily because it's the early work of Rich Hickey, famous for making the Clojure language.
sour-taste · 2 months ago
Doing this today I'd just have a std::function parameter and have callers pass in a lambda. I may use a third party std::function that doesn't have the weird copy semantics though
vitus · 2 months ago
> I may use a third party std::function that doesn't have the weird copy semantics though

Note that C++23 brings std::move_only_function if you're storing a callback for later use, as well as std::function_ref if you don't need lifetime extension.

https://en.cppreference.com/w/cpp/utility/functional/move_on...

plorkyeran · 2 months ago
This paper is about the idea that eventually became std::function.
mwkaufma · 2 months ago
Red flags for me when I see nonstandard functors in a c++ codebase (esp if the "glue" is in a setup function independent of the objects):

(i) Have they thought about the relative lifetimes of the sender and receiver?

(ii) Is the callback a "critical section" where certain side-effects have undefined behavior?

(iii) Does the functors store debugging info that .natvis can use?

(iv) Is it reeeeeeeally that bad to just implement an interface?

kazinator · 2 months ago
> Red flags for me when I see nonstandard functors in a c++ codebase

Even if it's 1994???

mwkaufma · 2 months ago
Yes in 1994 I had these exact judgements, at age 11 :P
tcbawo · 2 months ago
Can you elaborate on your third point? What would a class need to do to affect debugging info?

Regarding your fourth point, sometimes an architecture can be vastly simplified if the source of information can abstracted away. For example, invoking a callback from a TCP client, batch replay service, unit test, etc. Sometimes object oriented design gets in the way.

To your first point, I think RAII and architecture primarily address this. I'm not sure that I see callback implementation driving this. Although I have seen cancellable callbacks, allowing the receiver to safely cancel a callback when it goes away.

mwkaufma · 2 months ago
>> Can you elaborate on your third point? What would a class need to do to affect debugging info?

Common implementations are a function pointer + void* pair, which in most debuggers just show you two opaque addresses. Better to include a info block -- at least in debug builds -- with polymorphic type pointers that can actually deduce the type and show you all the fields of the receiver.

>> sometimes an architecture can be vastly simplified if the source of information can abstracted away.

"sometimes" is doing a lot of heavy lifting here. That's my whole point -- more often than not I see some type of homespun functor used in cases that are _not_ simplified, but actually complicated by the unnecessary "plumbing."

>> RAII and architecture primarily address this

If the receiver uses RAII to clean up the callback, then you've reintroduced the "type-intrusiveness" that functors are meant to avoid...?

pjmlp · 2 months ago
The only "standard" in 1994 was the C++ARM book (filled a similar role to the K&R C book) that served as basis for the ongoing standardization process, to be done in 1998.
mwkaufma · 2 months ago
Apologies, I didn't mean "standard" as in the C++ language standard, but standard as in provided-by-your-app-framework's-foundation-library.