alt Hacker NewsHow is Func0 / Func1<T> better than std::function?
Smaller size at runtime (uses less memory).
Smaller generated code.
Faster at runtime.
Faster compilation times.
Smaller implementation.
Implementation that you can understand.
How is it worse?
std::function + lambda with variable capture has better ergonomics i.e. less typing.
Replies
You can't just keep claiming these things without providing evidence. How much faster? How much smaller? These claims are meaningless without numbers to back it up.
I think the one key downside for std::function+lambda which resonated with me was bad ergonomics during debugging.
My unanswered question on this from 8 years ago:
https://stackoverflow.com/questions/41385439/named-c-lambdas...
If there was a way to name lambdas for debug purposes then all other downsides would be irrelevant (for most usual use cases of using callbacks).
Your Func thing is better than std::function the same way a hammer is better than a drill press... ie it's not better because it's not the same thing at all. Yes the hammer can do some of the same things, at a lower complexity, but it can't do all the same things.
What I'm trying to say is being better than x means you can do all the same things as x better. Your thing is not better, it is just different.
None of the arguments on this list seem convincing. The only one that makes sense was the argument that it helps identify the source of a crash.
How much smaller is it? Does it reduce the binary size and RAM usage by just 100 bytes?
Is it actually faster?
How much faster does it compile? 2ms faster?
> Smaller size at runtime (uses less memory).
Yours is smaller (in terms of sizeof), because std::function employs small-buffer optimization (SBO). That is if the user data fits into a specific size, then it's stored inline the std::function, instead of getting heap allocated. Yours need heap allocation for the ones that take data.
Whether yours win or lose on using less memory heavily depends on your typical closure sizes.
> Faster at runtime
Benchmark, please.
I think none of these points are demonstrated in the post hence I fail to visualize it
Also I copy pasted the code from the post and I got this:
test.cpp:70:14: error: assigning to 'void ' from 'func0Ptr' (aka 'void ()(void *)') converts between void pointer and function pointer 70 | res.fn = (func0Ptr)fn;