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Don’t blindly prefer emplace_back to push_back

(quuxplusone.github.io)
178 points todsacerdoti | 2 comments | 04 Mar 21 08:02 UTC | HN request time: 0.437s | source
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jokoon ◴[04 Mar 21 10:40 UTC] No.26340841[source]▶
Thanks for the article, there should be a huge list of those type of classic C++ misconceptions/FAQ style.

One of my favorite is "you don't need a linked list".

Although I'm still genuinely interested when a linked list is best suited. I'm also curious why they were invented and why they're taught, maybe just for teaching purposes...

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1. lorenzhs ◴[04 Mar 21 11:22 UTC] No.26341090[source]▶
Several few decades ago, pointer chasing was much cheaper because the difference between an arithmetic operation and a memory access was far lower. CPUs in those times didn't even have caches (because they weren't needed). That made linked lists a reasonable choice. But CPU and memory speeds have been diverging -- both are growing at an exponential pace, but with different exponents, so the gap is also growing exponentially! So now we have a huge memory hierarchy and random accesses into memory are really slow and linked lists rarely make sense.
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2. masklinn ◴[04 Mar 21 11:36 UTC] No.26341165[source]▶
> Several few decades ago, pointer chasing was much cheaper because the difference between an arithmetic operation and a memory access was far lower.

Also allocation was just bumping the brk.