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by throwaway894345
1312 days ago
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Eh, I've waffled a couple of times between "pass values by default" and "pass pointers by default". Ultimately, I don't think there's a really good answer except to understand escape analysis and get comfortable with the escape analyzer. Notably, "using pointers" doesn't inherently put pressure on the GC, but rather allocations put pressure on the GC and there are plenty of instances where pointers don't put pressure on the GC at all (notably, if you're passing data into a function by pointer, it's not going to allocate, but it may if you're returning a pointer to "a stack-allocated value"). Notably, if you're defaulting to values, you may still have a bunch of allocations when you try to implement interfaces, which usually (always?) requires implicitly boxing values; however, if you pass a pointer into a function that takes an interface, I don't think it gets moved to the heap (but I'm not sure, which is why Go programmers need to be comfortable with profiling the escape analyzer and also why it would be great if Go actually had explicit semantics for allocations). |
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Isn't it still possible for the value to escape here? For example the callee could stick it until a global data structure.
In fact it seems like a pointer passed to a function would need to be on the heap "by default" unless the compiler can prove that it doesn't escape.