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0 pointsnyanpasu645y ago0 comments

std::span is a modern C++ class designed to act like an array or vector, by viewing the memory of an existing array/vector without allocating anything. In my experience writing audio code, C++'s implicit copy constructors are what makes it too easy to accidentally allocate memory.

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qppo5y ago· 2 in thread

I'm not saying C++ is the best language out there but that smells like inexperience writing real-time safe code. The problem isn't implicit copy constructors but implicit copies in your code.

nyanpasu64OP5y ago

> The problem isn't implicit copy constructors but implicit copies in your code.

I don't understand what's the difference.

I'm not an expert in writing real-time safe code, but I've spent close to a year working on allocation-free programming. Implicit copies of structs (value types) are as fast as implicit copies of integers, but implicit copies of types with owned heap memory invoke the copy constructor, which calls into the allocator. Or did I misunderstand your comment or get anything wrong?

qppo5y ago

Sorry I worded that poorly, what I meant is that you shouldn't be writing code where the fact an implicit copy constructor allocates is a concern at all, because C++ has very clear copy semantics.

With a handful of exceptions you essentially will never need to worry about this if you restrict assignment and argument passing of non-POD types to references within the critical code blocks. And in the case that you do need to worry about it, the copy constructor should be explicitly deleted anyway.

It's a footgun to be sure, but it's not a serious one with a bit of discipline. If you're used to doing real-time safe programming, you'll get paranoid about code that could invoke an allocator (or write your own).

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